Merge pull request 'chore: remove unused .gitlab-ci.yml' (#249) from remove-gitlab-ci into main

Reviewed-on: https://gitea.unbound.se/unboundsoftware/auth0mock/pulls/249

.gitlab-ci.yml

@@ -1,17 +0,0 @@
-include:
-- template: 'Workflows/MergeRequest-Pipelines.gitlab-ci.yml'
-- project: unboundsoftware/ci-templates
-  file: Defaults.gitlab-ci.yml
-- project: unboundsoftware/ci-templates
-  file: Release.gitlab-ci.yml
-
-stages:
-- build
-
-image: buildtool/build-tools:${BUILDTOOLS_VERSION}
-
-build:
-  stage: build
-  script:
-  - build
-  - push