chore(gh-actions): fix setup-python warning

fix this warning:

```
Warning: Neither 'python-version' nor 'python-version-file' inputs were supplied. Attempting to find '.python-version' file.
Warning: .python-version doesn't exist.
Warning: The `python-version` input is not set.  The version of Python currently in `PATH` will be used.
```

Author: PhML

.github/workflows/pandora_ci.yml

@@ -58,6 +58,8 @@ jobs:
           fetch-depth: 0
 
       - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
 
       - name: Install build
         run: python -m pip install build