CI: run tests with oldest support pyproject-metadata

pyproject-metadata 0.8.0 has been released, keep one CI job testing
with the oldest supported version to ensure regressions are not
introduced.

Author: dnicolodi

.github/workflows/tests.yml

@@ -49,6 +49,8 @@ jobs:
           - '3.12'
         meson:
           -
+        pyproject_metadata:
+          -
         include:
           - os: ubuntu
             python: 'pypy-3.9'
@@ -88,6 +90,10 @@ jobs:
           - os: windows
             python: '3.12'
             meson: '@git+https://github.com/mesonbuild/meson.git'
+          # Test with oldest supported pyproject-metadata
+          - os: ubuntu
+            python: '3.12'
+            pyproject_metada: '==0.7.1'
 
     steps:
       - name: Checkout
@@ -114,8 +120,13 @@ jobs:
         run: python -m pip install "meson ${{ matrix.meson }}"
         if: ${{ matrix.meson }}
 
+      - name: Install pyproject-metadata
+        run: python -m pip install "pyproject-metadata ${{ matrix.pyproject_metadata }}
+        if: ${{ matrix.pyproject_metadata }}
+
       - name: Install
-        run: python -m pip install .[test]
+        run: |
+          python -m pip install .[test]
 
       - name: Run tests
         run: >-