fix workflow: just update to latest ubuntu image

Author: dhontecillas

.github/workflows/go.yml

@@ -8,14 +8,14 @@ on:
 
 jobs:
   build:
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Test
       uses: docker://krakend/builder:latest-linux-generic
       with:
         args: sh -c "go get -t -v ./...;
          gofmt -w -s . && git diff --exit-code;
          go tool vet .;
-         go test -v -race ./..."
+         go test -v -race ./..."