libsystemd: correct required_conan_version, add v255.2

[valgur]

Fixes the outdated required_conan_version value, as mentioned at #22436 (comment) by @bhutch29

[ghost]

I detected other pull requests that are modifying libsystemd/all recipe:

• libsystemd: Include libudev #20290
• [libsystemd] add libcrypt as dependency - more backports #18560

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[conan-center-bot]

Conan v1 pipeline ✔️

All green in build 2 (65749643273b8f3682f5c5a9f05cc7b099b0a34e):

• libsystemd/255:
  All packages built successfully! (All logs)

• libsystemd/253.14:
  All packages built successfully! (All logs)

• libsystemd/253.10:
  All packages built successfully! (All logs)

• libsystemd/255.2:
  All packages built successfully! (All logs)

• libsystemd/251.15:
  All packages built successfully! (All logs)

• libsystemd/253.6:
  All packages built successfully! (All logs)

• libsystemd/252.9:
  All packages built successfully! (All logs)

• libsystemd/249.16:
  All packages built successfully! (All logs)

• libsystemd/248.12:
  All packages built successfully! (All logs)

• libsystemd/247.13:
  All packages built successfully! (All logs)

• libsystemd/246.16:
  All packages built successfully! (All logs)

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Conan v2 pipeline ✔️

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

All green in build 2 (65749643273b8f3682f5c5a9f05cc7b099b0a34e):

• libsystemd/253.10:
  All packages built successfully! (All logs)

• libsystemd/255:
  All packages built successfully! (All logs)

• libsystemd/253.14:
  All packages built successfully! (All logs)

• libsystemd/253.6:
  All packages built successfully! (All logs)

• libsystemd/255.2:
  All packages built successfully! (All logs)

• libsystemd/251.15:
  All packages built successfully! (All logs)

• libsystemd/249.16:
  All packages built successfully! (All logs)

• libsystemd/248.12:
  All packages built successfully! (All logs)

• libsystemd/247.13:
  All packages built successfully! (All logs)

• libsystemd/252.9:
  All packages built successfully! (All logs)

• libsystemd/246.16:
  All packages built successfully! (All logs)