ci: Add .NET 9 build actions (#1275)

.gitattributes

@@ -1,2 +1,2 @@
 # Normalize line endings.
-* text=lf
+* text=auto eol=lf

.github/workflows/deploy-package.yml

@@ -37,7 +37,7 @@ jobs:
       - name: Setup .NET
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: "8.x"
+          dotnet-version: "9.x"
           dotnet-quality: "ga"
 
       - name: Setup GitVersion

.github/workflows/test-indicators.yml

@@ -21,16 +21,17 @@ jobs:
       matrix:
         os: [windows-latest, ubuntu-latest, macos-latest]
         dotnet-version: ["9.x"]
-        # TODO: restore when runners have 9.x on all
+        # TODO: restore when GitHub Action runners
+        #      have .NET 9.x SDK default installed
         # ["2.1.x", "6.x", "9.x"]
 
     env:
 
       # identifying primary configuration so only one reports coverage
       IS_PRIMARY: ${{ matrix.os == 'ubuntu-latest' && matrix.dotnet-version == '9.x' }}
 
-      # .NET SDK versions in the matrix that support `ga` quality spec
-      #   versions before 5.x do not support it
+      # .NET SDK versions in the matrix that support
+      # `dotnet-quality: 'ga'`, not supported before 5.x
       SUPPORT_GA: ${{ contains(fromJson('["6.x", "9.x"]'), matrix.dotnet-version) }}
 
     steps:

.github/workflows/test-integration.yml

@@ -26,7 +26,7 @@ jobs:
         id: dotnet-new
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: "8.x"
+          dotnet-version: "9.x"
           dotnet-quality: "ga"
 
       - name: Build library