chore(ci): Bump action-migrations to v1.4.0 (#127723)

Bumps
[action-migrations](https://github.com/getsentry/action-migrations/releases/tag/v1.4.0)
so the migration SQL comment is replaced instead of duplicated when
migration files are renamed or renumbered
(getsentry/action-migrations#36). Existing duplicate comments are
cleaned up on the next run.

Author: wedamija

.github/workflows/migrations.yml

@@ -72,7 +72,7 @@ jobs:
           echo 'EOF' >> "$GITHUB_OUTPUT"
 
       - name: Generate SQL for migration
-        uses: getsentry/action-migrations@9f4400077fa0d5216d2f251d3228380e5a774d7d # v1.3.0
+        uses: getsentry/action-migrations@da718e78dc50bb8068806f40271b65a5b4d75a0d # v1.4.0
         env:
           SENTRY_LOG_LEVEL: ERROR
         with: