ci(pytest): get changes for three trigger scenarios

.github/workflows/python-pull-request.yml

@@ -39,7 +39,18 @@ jobs:
     - name: Detect changed packages
       id: changed-packages
       run: |
-        CHANGED_FILES=$(git diff --name-only ${{ github.event.before }} ${{ github.sha }})
+        if [ "${{ github.event_name }}" == "pull_request" ]; then
+          # For pull requests, compare with the PR base
+          CHANGED_FILES=$(git diff --name-only ${{ github.event.pull_request.base.sha }} ${{ github.sha }})
+        elif [ "${{ github.event_name }}" == "push" ]; then
+          # For pushes, compare with the previous commit
+          git fetch --depth=2 origin ${{ github.ref }}
+          CHANGED_FILES=$(git diff --name-only HEAD^ HEAD)
+        else
+          # For scheduled runs, check all files
+          CHANGED_FILES=$(git ls-files '*.py')
+        fi
+
         echo "training_changed=$(echo "$CHANGED_FILES" | grep -q '^training/.*\.py$' && echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
         echo "graphs_changed=$(echo "$CHANGED_FILES" | grep -q '^graphs/.*\.py$' && echo 'true' || echo 'false')" >> $GITHUB_OUTPUT
         echo "models_changed=$(echo "$CHANGED_FILES" | grep -q '^models/.*\.py$' && echo 'true' || echo 'false')" >> $GITHUB_OUTPUT