ci: Bump codecov/codecov-action to v7.0.0.

Fixes broken GPG validation.
see codecov/codecov-action#1956

Author: seifertm

.github/workflows/main.yml

@@ -157,7 +157,7 @@ jobs:
         coverage combine
         coverage xml
     - name: Upload coverage report
-      uses: codecov/codecov-action@e79a6962e0d4c0c17b229090214935d2e33f8354  # v6.0.1
+      uses: codecov/codecov-action@fb8b3582c8e4def4969c97caa2f19720cb33a72f  # v7.0.0
       with:
         files: coverage.xml
         fail_ci_if_error: true