ci: drop python 3.7

The latest GitHub actions does not support it anymore.

Author: sbidoul

.github/workflows/check.yml

@@ -30,9 +30,6 @@ jobs:
     # Install supported Python versions. Keep in sync with noxfile.py as
     # much as possible, however, GitHub Actions eventually drops support
     # for EOL Python versions, at which point we can't test them in CI.
-    - uses: actions/setup-python@v5
-      with:
-        python-version: "3.7"
     - uses: actions/setup-python@v5
       with:
         python-version: "3.8"