gh: add govulncheck

Fixes #599

.github/workflows/govulncheck.yml

@@ -0,0 +1,29 @@
+---
+name: Vulnerability check
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+    paths:
+      - 'go.mod'
+      - 'go.sum'
+
+jobs:
+  govulncheck:
+    runs-on: ubuntu-latest
+    name: Run govulncheck
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set version env variables
+        run: |
+          cat .version >> $GITHUB_ENV
+
+      - id: Run govulncheck
+        uses: golang/govulncheck-action@v1
+        with:
+          go-version-input: "${{env.GO_VERSION}}"
+          go-package: ./...