ci: ensure the generated code is up-to-date

See https://github.com/etcd-io/etcd/pull/14612#issue-1419792069
Signed-off-by: spacewander <spacewanderlzx@gmail.com>

.github/workflows/static-analysis.yaml

@@ -12,5 +12,9 @@ jobs:
         uses: golangci/golangci-lint-action@v3
         with:
           version: v1.49.0
+      - name: protoc
+        uses: arduino/setup-protoc@v1
+        with:
+          version: '3.14.0'
       - run: make verify
       - run: make fix