Update common Prometheus files

Signed-off-by: prombot <prometheus-team@googlegroups.com>

.circleci/config.yml

@@ -1,9 +1,7 @@
----
 version: 2.1
-
 orbs:
   go: circleci/go@0.2.0
-
+  prometheus: prometheus/prometheus@0.11.0
 jobs:
   test:
     parameters:
@@ -19,53 +17,52 @@ jobs:
         type: boolean
         default: true
     docker:
-    - image: circleci/golang:<< parameters.go_version >>
+      - image: circleci/golang:<< parameters.go_version >>
     working_directory: /go/src/github.com/prometheus/client_golang
     steps:
-    - checkout
-    - when:
-        condition: << parameters.use_gomod_cache >>
-        steps:
-        - go/load-cache:
-            key: v1-go<< parameters.go_version >>
-    - run: make check_license test
-    - when:
-        condition: << parameters.run_lint >>
-        steps:
-        - run: make lint
-    - when:
-        condition: << parameters.run_style_and_unused >>
-        steps:
-        - run: make style unused
-    - when:
-        condition: << parameters.use_gomod_cache >>
-        steps:
-        - go/save-cache:
-            key: v1-go<< parameters.go_version >>
-    - store_test_results:
-        path: test-results
-
+      - checkout
+      - when:
+          condition: << parameters.use_gomod_cache >>
+          steps:
+            - go/load-cache:
+                key: v1-go<< parameters.go_version >>
+      - run: make check_license test
+      - when:
+          condition: << parameters.run_lint >>
+          steps:
+            - run: make lint
+      - when:
+          condition: << parameters.run_style_and_unused >>
+          steps:
+            - run: make style unused
+      - when:
+          condition: << parameters.use_gomod_cache >>
+          steps:
+            - go/save-cache:
+                key: v1-go<< parameters.go_version >>
+      - store_test_results:
+          path: test-results
 workflows:
   version: 2
   client_golang:
     jobs:
-    # Refer to README.md for the currently supported versions.
-    - test:
-        name: go-1-13
-        go_version: "1.13"
-        run_lint: true
-    - test:
-        name: go-1-14
-        go_version: "1.14"
-        run_lint: true
-    - test:
-        name: go-1-15
-        go_version: "1.15"
-        run_lint: true
-    - test:
-        name: go-1-16
-        go_version: "1.16"
-        run_lint: true
-        # Style and unused/missing packages are only checked against
-        # the latest supported Go version.
-        run_style_and_unused: true
+      # Refer to README.md for the currently supported versions.
+      - test:
+          name: go-1-13
+          go_version: "1.13"
+          run_lint: true
+      - test:
+          name: go-1-14
+          go_version: "1.14"
+          run_lint: true
+      - test:
+          name: go-1-15
+          go_version: "1.15"
+          run_lint: true
+      - test:
+          name: go-1-16
+          go_version: "1.16"
+          run_lint: true
+          # Style and unused/missing packages are only checked against
+          # the latest supported Go version.
+          run_style_and_unused: true