Fixed faillint for ./integration tests (#3428)

Signed-off-by: Marco Pracucci <marco@pracucci.com>

Author: pracucci

Makefile

@@ -145,7 +145,7 @@ lint:
 	golangci-lint run
 
 	# Ensure no blacklisted package is imported.
-	faillint -paths "github.com/bmizerany/assert=github.com/stretchr/testify/assert,\
+	GOFLAGS="-tags=requires_docker" faillint -paths "github.com/bmizerany/assert=github.com/stretchr/testify/assert,\
 		golang.org/x/net/context=context,\
 		github.com/prometheus/prometheus/tsdb/errors=util,\
 		sync/atomic=go.uber.org/atomic" ./pkg/... ./cmd/... ./tools/... ./integration/...