Use old action directly in workflow

.github/workflows/main.yml

@@ -7,7 +7,28 @@ on:
 
 jobs:
   main:
-    uses: ocadotechnology/codeforlife-workspace/.github/workflows/backend.yaml@snyk
-    secrets: inherit
-    with:
-      source-path: src
+    runs-on: ubuntu-22.04
+    env:
+      LANG: C.UTF-8
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Setup python-version
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+          architecture: "x64"
+      - name: Install Python dependencies
+        run: |
+          pip install pipenv
+          pipenv install --dev --system
+      - name: Generate requirements
+        run: pip freeze > requirements.txt
+      - name: Run Snyk to check for vulnerabilities in Python
+        uses: snyk/actions/python@master
+        env:
+          SNYK_TOKEN: ${{ secrets.SNYK_TOKEN }}
+        with:
+          command: monitor --file=requirements.txt --package-manager=pip