update dependency github.com/prometheus/client_golang to v1.11.0

.circleci/config.yml

@@ -1,6 +1,6 @@
 version: 2
 jobs:
-  test1:
+  go1.16:
     docker:
       - image: circleci/golang:1.16-node
     working_directory: /go/src/github.com/fatedier/frp
@@ -8,7 +8,7 @@ jobs:
       - checkout
       - run: make
       - run: make alltest
-  test2:
+  go1.15:
     docker:
       - image: circleci/golang:1.15-node
     working_directory: /go/src/github.com/fatedier/frp
@@ -21,5 +21,5 @@ workflows:
   version: 2
   build_and_test:
     jobs:
-      - test1
-      - test2
+      - go1.16
+      - go1.15