Remove unused actions (#2653)

.github/workflows/semgrep.yml

@@ -1,20 +0,0 @@
-name: Semgrep
-on:
-  pull_request: {}
-  push:
-    branches:
-      - master
-
-jobs:
-  check:
-    if: "! startsWith(github.event.head_commit.message, '[CI Skip]') && (!github.event.pull_request || github.event.pull_request.head.repo.full_name == github.repository)"
-    runs-on: ubuntu-latest
-    env:
-      YARN_ENABLE_SCRIPTS: false
-    steps:
-      - uses: actions/checkout@7884fcad6b5d53d10323aee724dc68d8b9096a2e
-      - uses: returntocorp/semgrep-action@aeafd770072c4f48798b991e3449592bddc2c435
-        with:
-          auditOn: push
-          publishToken: ${{ secrets.SEMGREP_APP_TOKEN }}
-          publishDeployment: 1395