Run build & test steps on windows & macos if the ci/test label is set

Author: julienp

Diff for: .github/workflows/pr.yml

@@ -14,12 +14,31 @@ env:
   PULUMI_TEST_OWNER: "moolumi"
 
 jobs:
+  setup_matrix:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+    steps:
+      - id: set-matrix
+        run: |
+          os=${{ contains(github.event.pull_request.labels.*.name, 'ci/test') && 'macos-latest windows-latest' || 'ubuntu-latest' }}
+          echo "matrix={\"os\": $(echo $os | jq -cR 'split(" ")')}" >> $GITHUB_OUTPUT
+
+  debug:
+    runs-on: ubuntu-latest
+    needs: setup_matrix
+    steps:
+      - name: Debug
+        run: echo "${{ needs.setup_matrix.outputs.matrix }}"
+
   build:
+    needs: setup_matrix
     strategy:
       matrix:
+        os: ${{ fromJson(needs.setup_matrix.outputs.matrix).os }}
         dotnet-version: [6.0.x, 8.0.x]
 
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
@@ -47,9 +66,9 @@ jobs:
           token: ${{ secrets.CODECOV_TOKEN }}
   integration-tests:
     strategy:
-        matrix:
-          os: [ubuntu-latest, windows-latest, macos-11]
-          dotnet-version: [6.0.x, 8.0.x]
+      matrix:
+        os: [ubuntu-latest, windows-latest, macos-11]
+        dotnet-version: [6.0.x, 8.0.x]
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout code