chore(ci): update go.yaml support golang 1.20 (#2651)

.github/workflows/go.yml

@@ -13,7 +13,7 @@ jobs:
   build:
     strategy:
       matrix:
-        go: [1.18,1.19]
+        go: [1.18,1.19,1.20.x]
     name: build & test
     runs-on: ubuntu-latest
     services:
@@ -82,4 +82,4 @@ jobs:
         run: |
           cd cmd/protoc-gen-go-http
           go build ./...
-          go test ./...
+          go test ./...