github workflows: add go fmt, vet checks

.github/workflow-scripts/check-gofmt.sh

@@ -0,0 +1,11 @@
+#!/bin/sh
+
+set -ue
+
+fmt_list="$(gofmt -l "$@")"
+
+if [ -n "$fmt_list" ]; then
+  echo "Check gofmt failed: " >&2
+  echo "${fmt_list}" | sed -e 's/^/\t/' >&2
+  exit 1
+fi

.github/workflows/build.yml

@@ -25,12 +25,18 @@ jobs:
       - name: Download dependencies
         run: go mod download
 
+      - name: Check gofmt
+        run: .github/workflow-scripts/check-gofmt.sh .
+
       - name: Build
         run: go build -v
 
       - name: Test
         run: go test -v
 
+      - name: Vet
+        run: go vet
+
       - name: Upload
         uses: actions/upload-artifact@v3
         with: