Test using Python 3.13 + drop Python 3.8 (#546)

Author: macbre

.github/workflows/python-ci.yml

@@ -18,11 +18,11 @@ jobs:
         # https://github.com/actions/python-versions/blob/main/versions-manifest.json
         # https://devguide.python.org/versions/#supported-versions
         python-version:
-        - "3.8"
         - "3.9"
         - "3.10"
         - "3.11"
         - "3.12"
+        - "3.13"
 
     steps:
     - uses: actions/checkout@v4
@@ -70,10 +70,12 @@ jobs:
     # https://coveralls-python.readthedocs.io/en/latest/usage/index.html
     # upload coverage report for just one of Python version matrix runs
     - name: Upload coverage report to Coveralls
-      if: matrix.python-version == '3.9'
+      if: matrix.python-version == '3.12'
       env:
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-      run: poetry run coveralls --service=github || true
+      run: |
+        pip install coveralls
+        poetry run coveralls --service=github
 
     - name: Lint with pylint
       run: make lint