CI: test also with pyproject-metadata 0.8.0

Author: dnicolodi

.github/workflows/tests.yml

@@ -95,10 +95,13 @@ jobs:
           - os: windows-latest
             python: '3.12'
             meson: '@git+https://github.com/mesonbuild/meson.git'
-          # Test with oldest supported pyproject-metadata
+          # Test with older supported pyproject-metadata
           - os: ubuntu-latest
             python: '3.12'
             pyproject_metadata: '==0.7.1'
+          - os: ubuntu-latest
+            python: '3.12'
+            pyproject_metadata: '==0.8.0'
 
     steps:
       - name: Checkout