ci: enable semgrep workflow

.github/workflows/semgrep.yml

@@ -0,0 +1,39 @@
+name: Semgrep
+
+on:
+  pull_request:
+    branches: ["dev"]
+
+permissions:
+  actions: read
+  contents: read
+  security-events: write
+
+jobs:
+  semgrep:
+    name: semgrep/ci
+    runs-on: ubuntu-latest
+
+    container:
+      image: returntocorp/semgrep
+
+    # Skip any PR created by dependabot to avoid permission issues:
+    if: ${{ github.actor != 'dependabot[bot]' }}
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          show-progress: false
+
+      - name: "Run the 'semgrep ci' command on the command line of the docker image."
+        run: semgrep ci --sarif --output=semgrep.sarif --config auto --config "p/gitlab" --exclude-rule yaml.github-actions.security.third-party-action-not-pinned-to-commit-sha.third-party-action-not-pinned-to-commit-sha
+        env:
+          # Add the rules that Semgrep uses by setting the SEMGREP_RULES environment variable.
+          # more at semgrep.dev/explore
+          SEMGREP_RULES: p/default
+
+      - name: Upload SARIF file for GitHub Advanced Security Dashboard
+        if: always()
+        uses: github/codeql-action/upload-sarif@v2
+        with:
+          sarif_file: semgrep.sarif