Added GHA job to only run PR workflow in case code has been changed

.github/workflows/pr.yml

@@ -8,31 +8,54 @@ on:
 
 jobs:
 
+  detect_code_changes:
+    runs-on: ubuntu-latest
+    outputs:
+      code_changes: ${{ steps.filter.outputs.code_changes }}
+    steps:
+      - uses: dorny/paths-filter@v3
+        id: changes
+        with:
+          filters: |
+            code_changes:
+              - 'quinn/**'
+              - 'tests/**'
+              - 'benchmarks/**'
+              - '.github/**'
+              - 'poetry.lock'
+              - 'pyproject.toml'
+
   test:
     runs-on: ubuntu-latest
+    needs: [detect_code_changes]
     steps:
       - uses: actions/checkout@v3
+        if: needs.detect_code_changes.outputs.code_changes == 'true'
         with:
           fetch-depth: 1
 
       - name: Setup Java
         uses: actions/setup-java@v3
+        if: needs.detect_code_changes.outputs.code_changes == 'true'
         with:
           distribution: 'zulu'
           java-version: '8'  # Supported by Spark 2.x & 3.x
 
       - name: Set up Python 3.9
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
+        if: needs.detect_code_changes.outputs.code_changes == 'true'
         with:
           python-version: 3.9
 
       - name: Install Poetry
         uses: snok/install-poetry@v1
+        if: needs.detect_code_changes.outputs.code_changes == 'true'
         with:
           version: 1.6.1
 
       - name: Cache Poetry virtualenv
         uses: actions/cache@v1
+        if: needs.detect_code_changes.outputs.code_changes == 'true'
         id: cache
         with:
           path: ~/.virtualenvs
@@ -41,8 +64,12 @@ jobs:
             poetry-${{ hashFiles('**/poetry.lock') }}
 
       - name: Install dependencies
+        if: |
+          needs.detect_code_changes.outputs.code_changes == 'true' &&
+          steps.cache.outputs.cache-hit != 'true'
         run: make install_test
-        if: steps.cache.outputs.cache-hit != 'true'
+        # if: steps.cache.outputs.cache-hit != 'true'
 
       - name: Run tests with pytest
+        if: needs.detect_code_changes.outputs.code_changes == 'true'
         run: make test