TST: skip tests for draft PRs and non-Python files

Author: giovaniceotto

.github/workflows/test_pytest.yaml

@@ -1,9 +1,19 @@
 name: PyTest
 
-on: [pull_request]
+on:  
+  pull_request:
+    types: [opened, synchronize, reopened, ready_for_review]
+    paths:
+      - '**.py'
 
 jobs:
-  build:
+  fail_if_pull_request_is_draft:
+      if: github.event.pull_request.draft == true
+      runs-on: ubuntu-18.04
+      steps:
+      - name: Fails in order to indicate that pull request needs to be marked as ready to review and unit tests workflow needs to pass.
+        run: exit 1
+  run_pytest_and_doctest:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -31,4 +41,4 @@ jobs:
       run: |
         pytest
         cd rocketpy
-        pytest --doctest-modules
+        pytest --doctest-modules