⬆️ update golangci/golangci-lint to 1.18.0

This resolves issue golangci/golangci-lint#658 when compiling with go1.13.

Author: ccamel

Makefile

@@ -10,7 +10,7 @@ default: build
 install-tools:
 	@if [ ! -f $(GOPATH)/bin/golangci-lint ]; then \
 		echo "installing golangci-lint..."; \
-		curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(GOPATH)/bin v1.17.1; \
+		curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(GOPATH)/bin v1.18.0; \
 	fi
 	@if [ ! -f $(GOPATH)/bin/goconvey ]; then \
 		echo "installing goconvey..."; \