Bump python version so linter works again

Looks like GitHub's setup-python action dropped support for Python 3.7.

The Python version hopefully doesn't matter for running vint?

Author: jez

.github/workflows/vint.yml

@@ -9,7 +9,7 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v1
       with:
-        python-version: 3.7
+        python-version: 3.13
     - name: Setup dependencies
       run: pip install vim-vint
     - name: Run Vimscript Linter