ci: update go.yml workflow to modern version

Author: OpenClaw

.github/workflows/go.yml

@@ -1,28 +1,25 @@
 name: Go
-on: [push]
-jobs:
+on: [push, pull_request]
 
+jobs:
   build:
     name: Build
     runs-on: ubuntu-latest
     steps:
+    - name: Check out code
+      uses: actions/checkout@v4
 
-    - name: Set up Go 1.12
-      uses: actions/setup-go@v1
+    - name: Set up Go
+      uses: actions/setup-go@v5
       with:
-        go-version: 1.12
-      id: go
-
-    - name: Check out code into the Go module directory
-      uses: actions/checkout@v1
+        go-version: '1.21'
+        cache: true
 
     - name: Get dependencies
-      run: |
-        go get -v -t -d ./...
-        if [ -f Gopkg.toml ]; then
-            curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
-            dep ensure
-        fi
+      run: go mod download
 
     - name: Build
-      run: go build -v .
+      run: go build -v ./...
+
+    - name: Test
+      run: go test -v -race ./...