Remove Semgrep GHA Workflow (#735)

Author: tanya732

.github/workflows/semgrep.yml

@@ -1,24 +0,0 @@
-name: Semgrep
-
-on:
-  pull_request: {}
-
-  push:
-    branches: ["master", "main"]
-
-  schedule:
-    - cron: '30 0 1,15 * *'
-
-jobs:
-  semgrep:
-    name: Scan
-    runs-on: ubuntu-latest
-    container:
-      image: returntocorp/semgrep
-    if: (github.actor != 'dependabot[bot]')
-    steps:
-      - uses: actions/checkout@v6
-
-      - run: semgrep ci
-        env:
-          SEMGREP_APP_TOKEN: ${{ secrets.SEMGREP_APP_TOKEN }}