Fix golint errors

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/certmanager/acme_challenge_handler.go

@@ -71,7 +71,7 @@ func (h *ACMEChallengeHandler) Handle(next http.Handler) http.Handler {
 
 		w.Header().Set("Content-Type", "text/plain")
 		w.WriteHeader(http.StatusOK)
-		w.Write([]byte(keyAuth))
+		_, _ = w.Write([]byte(keyAuth))
 	})
 }