build: fix broken stylua action

Author: sudo-tee

.github/workflows/tests.yml

@@ -18,7 +18,7 @@ jobs:
       - uses: JohnnyMorganz/stylua-action@v4
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
-          version: latest
+          version: v2.1.0
           args: --check . -g '*.lua' -g '!deps/'
 
   test: