Pin GitHub Actions workflows to a specific version (#67)

Author: ErikSchierboom

.github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
     name: Test Analyzer
     runs-on: ubuntu-22.04
     steps:
-      - uses: actions/checkout@v1
+      - uses: actions/checkout@50fbc622fc4ef5163becd7fab6573eac35f8462e
 
       - name: Build Docker Image
         run: docker build -f Dockerfile -t python-analyzer .