ci: do not run chromatic on fork repositories

Author: anatawa12

.github/workflows/storybook.yml

@@ -15,6 +15,8 @@ on:
 
 jobs:
   build:
+    # chromatic is not likely to be available for fork repositories, so we disable for fork repositories.
+    if: github.repository == 'misskey-dev/misskey'
     runs-on: ubuntu-latest
 
     env: