Update Python version from 3.7 to 3.8 in CI workflow

### Notes

- Change python-version from 3.7 to 3.8 in test matrix
- Python 3.7 reached end-of-life and is no longer available on Ubuntu 24.04
- Python 3.8 is widely supported and compatible with the project requirements

### Testing

This addresses the CI failure where Python 3.7 was not found in the local cache
for Ubuntu 24.04. Python 3.8 should be available and allow the workflow to proceed.

### Issues
* Fixes Python version availability issue in GitHub Actions workflow

Author: natsirtguy

.github/workflows/test.yml

@@ -19,7 +19,7 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         emacs_version: [26.3, 27.2, 28.2, 29.1]
-        python-version: [3.7]
+        python-version: [3.8]
 
     steps:
     - uses: actions/checkout@v4