Update .gitlab-ci.yml

.gitlab-ci.yml

 build:
     stage: build
+    tags: gitlab-runner
     script:
         - echo "Build"
         - mkdir build
@@ -9,6 +10,7 @@ build:
             - build/
 test:
     stage: test
+    tags: gitlab-runner
     script:
         - echo "Testing"
         - test -f "build/info.txt"
\ No newline at end of file