Adds retry to git fetch in db:migrate job

Retries checkout as sporadic 500 and hang up errors occur
Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/290851

.gitlab/ci/rails.gitlab-ci.yml

@@ -320,7 +320,7 @@ db:migrate-from-v12.10.0:
     - export TAG_TO_CHECKOUT="v12.10.0-ee"
     - '[[ -d "ee/" ]] || export PROJECT_TO_CHECKOUT="gitlab-foss"'
     - '[[ -d "ee/" ]] || export TAG_TO_CHECKOUT="v12.10.0"'
-    - git fetch https://gitlab.com/gitlab-org/$PROJECT_TO_CHECKOUT.git $TAG_TO_CHECKOUT
+    - retry 'git fetch https://gitlab.com/gitlab-org/$PROJECT_TO_CHECKOUT.git $TAG_TO_CHECKOUT'
     - git checkout -f FETCH_HEAD
     - sed -i -e "s/gem 'grpc', '~> 1.24.0'/gem 'grpc', '~> 1.30.2'/" Gemfile  # Update gRPC for Ruby 2.7
     - sed -i -e "s/gem 'google-protobuf', '~> 3.8.0'/gem 'google-protobuf', '~> 3.12.0'/" Gemfile