simplify regex for gitdiff changed files detection

.github/workflows/coverage.yaml

@@ -18,25 +18,30 @@ jobs:
 
       - name: Fetch github branches and detect introduces .py files
         run: |
+          py_files=()
           if [ "${{ github.event.pull_request.head.repo.full_name }}" != "${{ github.repository }}" ]; then
               # Fetch changes when PR comes from remote repo
               git fetch origin +refs/heads/${{ github.base_ref }}:refs/remotes/origin/${{ github.base_ref }}
               git fetch origin +refs/pull/${{ github.event.pull_request.number }}/head:refs/remotes/origin/PR-${{ github.event.pull_request.number }}
-              files=$(git diff --name-status origin/${{ github.base_ref }}...origin/PR-${{ github.event.pull_request.number }} -- tests/ | grep -E '^[AM]' | grep '\.py$')
+              gitdiff=$(git diff --name-status origin/${{ github.base_ref }}...origin/PR-${{ github.event.pull_request.number }} -- tests/)
           else
               # Fetch the base branch and the head branch
               git fetch origin ${{ github.base_ref }}:refs/remotes/origin/${{ github.base_ref }}
               git fetch origin ${{ github.head_ref }}:refs/remotes/origin/${{ github.head_ref }}
-              files=$(git diff --name-status origin/${{ github.base_ref }}...origin/${{ github.head_ref }} -- tests/ | grep -E '^[AM]' | grep '\.py$')
+
+              gitdiff=$(git diff --name-status origin/${{ github.base_ref }}...origin/${{ github.head_ref }} -- tests/)
           fi
 
-          # Eliminate git diff chars, select only .py paths
-          echo "Collect the changed .py files"
-          py_files=()
-          while read -r line; do
-              file_fixed=$(echo "$line" | cut -c 3-)
-              py_files+=("$file_fixed")
-          done <<< "$files"
+          echo "git diff:"
+          echo "$gitdiff"
+          paths=$(echo "$gitdiff" | grep -oE '/[^[:space:]]+')
+          while IFS= read -r line; do
+            py_files+=("tests$line")
+          done <<< "$paths"
+          echo "Extracted file paths:"
+          for path in "${py_files[@]}"; do
+            echo "$path"
+          done
 
           echo "Prepare the NEW_TESTS variable"
           py_files_str=$(IFS=,; echo "${py_files[*]}")