feat(security): add github workflow to check dependencies

This workflow action uses OSV Scanner, an open source vulnerability
scanner by Google. We're using OSV Scanner because it has:

* good usability - JSON output and multiple options
* good accuracy - OSV database from google and support
  for multiple languages including PHP

.github/workflows/check-dependencies.yml

@@ -0,0 +1,19 @@
+name: Check dependencies
+
+# Adapted from https://google.github.io/osv-scanner/github-action/#scan-on-pull-request
+
+on:
+  pull_request:
+    branches: [main, 1.*.x]
+  merge_group:
+    branches: [main, 1.*.x]
+
+permissions:
+  # Require writing security events to upload SARIF file to security tab
+  security-events: write
+  # Only need to read contents
+  contents: read
+
+jobs:
+  scan-pr:
+    uses: "google/osv-scanner-action/.github/workflows/osv-scanner-reusable.yml@v1.7.1"

.github/workflows/osv-scanner.yml

@@ -1,27 +0,0 @@
-name: OSV Scanner
-
-on:
-  pull_request:
-  push:
-
-jobs:
-  OSV-Scanner:
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v3
-        with:
-          fetch-depth: 0
-
-      - name: Install Golang
-        uses: actions/setup-go@v4
-        with:
-          go-version: '1.19'
-
-      - name: Install OSV Scanner
-        run: |
-          go install github.com/google/osv-scanner/cmd/osv-scanner@latest
-
-      - name: Scan for Vulnerabilities
-        run: |
-          osv-scanner -r .