Updated CI pipeline config to only deploy to staging on the branch "staging".

.gitlab-ci.yml

@@ -29,7 +29,7 @@ build:
   - docker push "registry.gitlab.com/s3lph/matemat:$(git rev-parse HEAD)"
   - docker push registry.gitlab.com/s3lph/matemat:latest-staging
   only:
-  - /^staging-.*$/
+  - staging
 
 staging:
   stage: staging
@@ -41,4 +41,4 @@ staging:
     name: staging
     url: https://matemat.kernelpanic.lol/
   only:
-  - /^staging-.*$/
+  - staging