qt: fix setting cppstd

[SvenRoederer]

Summary

Changes to recipe: qt/6.x

Motivation

"current_cpp_std" is of type str, so the list elements that are indexed by it should also be of this type

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• [ X ] Read the contributing guidelines
• [ X ] Checked that this PR is not a duplicate: list of PRs by recipe
• [ X ] Tested locally with at least one configuration using a recent version of Conan

[conan-center-bot]

Conan v1 pipeline ❌

Failure in build 6 (13913e11fceedba5e42357b24279770b94f77467):

• qt/6.7.1:
  Didn't run or was cancelled before finishing

• qt/6.6.3:
  Didn't run or was cancelled before finishing

• qt/6.7.0:
  Didn't run or was cancelled before finishing

• qt/6.3.2:
  Didn't run or was cancelled before finishing

• qt/6.5.3:
  Didn't run or was cancelled before finishing

• qt/6.6.1:
  Didn't run or was cancelled before finishing

• qt/6.6.2:
  Didn't run or was cancelled before finishing

• qt/6.4.2:
  CI failed to create some packages (All logs)

  Logs for packageID 2894543c06ae0e7997798e731ed28e98f1156a79:

  [settings]
  arch=armv8
  build_type=Release
  compiler=apple-clang
  compiler.libcxx=libc++
  compiler.version=13.0
  os=Macos
  [options]
  qt:shared=False
  

  [...]
  Configuring submodule 'qtwayland'
  Configuring submodule 'qtwebchannel'
  Configuring submodule 'qtwebengine'
  Configuring submodule 'qtwebview'
  
  -- Configuration summary shown below. It has also been written to /Users/jenkins/workspace/prod-v1/bsr/64014/bcbee/.conan/data/qt/6.4.2/_/_/build/2894543c06ae0e7997798e731ed28e98f1156a79/build/Release/config.summary
  -- Configure with --log-level=STATUS or higher to increase CMake's message verbosity. The log level does not persist across reconfigurations.
  
  Note: Using static linking will disable the use of dynamically loaded plugins. Make sure to import all needed static plugins, or compile needed modules into the library.
  Note: When linking against OpenSSL, you can override the default library names through OPENSSL_LIBS. For example: OPENSSL_LIBS='-L/opt/ssl/lib -lssl -lcrypto' ./configure -openssl-linked
  
  WARNING: On OS X, AAT is supported only with -qt-harfbuzz.
  
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'libffi-release-armv8-data.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'autoconf-config.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'ZLIB-release-armv8-data.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'SQLite3ConfigVersion.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'autoconf-config-version.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'FindPostgreSQL.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'FindPNG.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'glib-release-armv8-data.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'PNGConfig.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'module-ODBC-release-armv8-data.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'md4c-config.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'module-SQLite3-release-armv8-data.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'freetype-config-version.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'FindIntl.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'FindIconv.cmake' file.
  qt/6.4.2: WARN: replace_in_file didn't find pattern ' IMPORTED)
  ' in 'm4-config-version.cmake' file.
  qt/6.4.2: ERROR: Package '2894543c06ae0e7997798e731ed28e98f1156a79' build failed
  qt/6.4.2: WARN: Build folder /Users/jenkins/workspace/prod-v1/bsr/64014/bcbee/.conan/data/qt/6.4.2/_/_/build/2894543c06ae0e7997798e731ed28e98f1156a79/build/Release
  ERROR: qt/6.4.2: Error in build() method, line 786
  	cmake.configure()
  	ConanException: Error 1 while executing cmake -G "Ninja" -DCMAKE_TOOLCHAIN_FILE="/Users/jenkins/workspace/prod-v1/bsr/64014/bcbee/.conan/data/qt/6.4.2/_/_/build/2894543c06ae0e7997798e731ed28e98f1156a79/build/Release/generators/conan_toolchain.cmake" -DCMAKE_INSTALL_PREFIX="/Users/jenkins/workspace/prod-v1/bsr/64014/bcbee/.conan/data/qt/6.4.2/_/_/package/2894543c06ae0e7997798e731ed28e98f1156a79" -DQT_USE_VCPKG="OFF" -DCMAKE_POLICY_DEFAULT_CMP0091="NEW" -DCMAKE_BUILD_TYPE="Release" "/Users/jenkins/workspace/prod-v1/bsr/64014/bcbee/.conan/data/qt/6.4.2/_/_/source/src"
  

• qt/6.6.0:
  Didn't run or was cancelled before finishing

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Conan v2 pipeline ✔️

Note: Conan v2 builds are now mandatory. Please read our discussion about it.

All green in build 4 (13913e11fceedba5e42357b24279770b94f77467):

• qt/6.6.2:
  All packages built successfully! (All logs)

• qt/6.7.1:
  All packages built successfully! (All logs)

• qt/6.7.0:
  All packages built successfully! (All logs)

• qt/6.6.1:
  All packages built successfully! (All logs)

• qt/6.5.3:
  All packages built successfully! (All logs)

• qt/6.6.3:
  All packages built successfully! (All logs)

• qt/6.6.0:
  All packages built successfully! (All logs)

• qt/6.4.2:
  All packages built successfully! (All logs)

• qt/6.3.2:
  All packages built successfully! (All logs)