ci: save cache by Python version

Author: jag1g13

.github/workflows/python-package.yml

@@ -42,10 +42,9 @@ jobs:
         # This path is specific to Ubuntu
         path: ${{ steps.pip-cache.outputs.dir }}
         # Look to see if there is a cache hit for the corresponding requirements file
-        key: ${{ runner.os }}-pip-${{ hashFiles('pyproject.toml') }}
+        key: ${{ runner.os }}-${{ matrix.python-version }}-pip-${{ hashFiles('pyproject.toml') }}
         restore-keys: |
-          ${{ runner.os }}-pip-
-          ${{ runner.os }}-    
+          ${{ runner.os }}-${{ matrix.python-version }}-pip-
 
     - name: Install dependencies
       run: |