Revert "Fix empty workflow"

This reverts commit 4b9c482384.

.github/workflows/sec_sast_flawfinder_pull.yml

@@ -1,28 +0,0 @@
----
-name: Semgrep Differential Scan
-on:
-  pull_request
-
-jobs:
-
-  semgrep-diff:
-    runs-on: ubuntu-latest
-    container:
-      image: returntocorp/semgrep
-
-    steps:
-
-      # step 1
-      - name: clone application source code
-        uses: actions/checkout@v3
-        with:
-          fetch-depth: 0
-
-      # step 2
-      - name: differential scan
-        run: |
-          semgrep scan \
-            --error \
-            --metrics=off \
-            --baseline-commit ${{ github.event.pull_request.base.sha }} \
-            --config="p/default"