Configure golangci-lint

Signed-off-by: Lantao Liu <lantaol@google.com>

.golangci.yml

@@ -18,5 +18,6 @@ run:
   deadline: 2m
   skip-dirs:
     - integration
+    - pkg/api
   skip-files:
-    - ".*_test.go" 
+    - ".*_test.go"

Makefile

@@ -190,7 +190,10 @@ install.tools: .install.gitvalidation .install.golangci-lint .install.vndr ## in
 
 .install.golangci-lint:
 	@echo "$(WHALE) $@"
-	$(GO) get -u github.com/golangci/golangci-lint/cmd/golangci-lint
+	$(GO) get -d github.com/golangci/golangci-lint/cmd/golangci-lint
+	@cd $(GOPATH)/src/github.com/golangci/golangci-lint/cmd/golangci-lint; \
+		git checkout v1.18.0; \
+		go install
 
 .install.vndr:
 	@echo "$(WHALE) $@"