.gitlab-ci.yml: do not run tests and builds on master

.gitlab-ci.yml

@@ -10,6 +10,8 @@ build-src:
   image: debian:buster
   variables:
     GOPATH: $CI_PROJECT_DIR
+  except:
+    - master
   script:
     - apt update
     - apt install -y curl gnupg git make golang
@@ -26,6 +28,8 @@ build-docker:
   image: docker:stable
   services:
     - docker:dind
+  except:
+    - master
   script:
     - docker build -t commento-ce .
 
@@ -40,6 +44,8 @@ go-test:
     POSTGRES_DB: commento_test
     COMMENTO_POSTGRES: postgres://postgres:postgres@postgres/commento_test?sslmode=disable
     GOPATH: $CI_PROJECT_DIR
+  except:
+    - master
   script:
     - mkdir -p src/gitlab.com/commento && cd src/gitlab.com/commento && ln -s $CI_PROJECT_DIR && cd $CI_PROJECT_NAME
     - make test
@@ -47,6 +53,8 @@ go-test:
 go-fmt:
   stage: go-fmt
   image: golang:1.10.2
+  except:
+    - master
   script:
     - cd api
     - test -z $(go fmt)