[gtk/ebassi/style-check] ci: Move style check to its own stage

[Emmanuele Bassi <ebassi src gnome org>]

commit 048ac9b4cb29313a650636fce6d2ecc4e5e5a57b
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Fri Sep 9 23:39:20 2022 +0100

    ci: Move style check to its own stage
    
    Drop the `.pre` phase.

 .gitlab-ci.yml | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 495dfea98e..8829a100c0 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -3,6 +3,7 @@ include:
     file: 'flatpak/flatpak_ci_initiative.yml'
 
 stages:
+  - check
   - build
   - analysis
   - docs
@@ -37,7 +38,7 @@ variables:
 style-check-diff:
   extends: .only-default
   image: $FEDORA_IMAGE
-  stage: .pre
+  stage: check
   allow_failure: true
   script:
     - .gitlab-ci/run-style-check-diff.sh