add vet back to drone but remove GOOS and GOARCH when build vet

Author: lunny

.drone.yml

@@ -37,7 +37,7 @@ steps:
     pull: always
     image: golang:1.15
     commands:
-      - make golangci-lint
+      - make golangci-lint vet
     environment:
       GOPROXY: https://goproxy.cn # proxy.golang.org is blocked in China, this proxy is not
       GOSUMDB: sum.golang.org

Makefile

@@ -232,7 +232,7 @@ fmt:
 vet:
 	@echo "Running go vet..."
 	@$(GO) vet $(GO_PACKAGES)
-	@$(GO) build -mod=vendor code.gitea.io/gitea-vet
+	@GOOS= GOARCH= $(GO) build -mod=vendor code.gitea.io/gitea-vet
 	@$(GO) vet -vettool=gitea-vet $(GO_PACKAGES)
 
 .PHONY: $(TAGS_EVIDENCE)