Add Semgrep GHA

.github/workflows/semgrep.yaml

@@ -0,0 +1,41 @@
+name: Semgrep
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  semgrep:
+    name: semgrep/ci
+    runs-on: ubuntu-latest
+
+    permissions:
+      security-events: write
+      actions: read
+      contents: read
+
+    container:
+      image: semgrep/semgrep
+
+    # Skip any PR created by dependabot to avoid permission issues:
+    if: (github.actor != 'dependabot[bot]')
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - run: semgrep ci --sarif > semgrep.sarif
+        env:
+          SEMGREP_APP_TOKEN: ${{ secrets.SEMGREP_APP_TOKEN }}
+
+      - name: Upload SARIF file for GitHub Advanced Security Dashboard
+        uses: github/codeql-action/upload-sarif@v2
+        with:
+          sarif_file: semgrep.sarif
+        if: always()