Remove jQuery class from the commit button (go-gitea#30178)

- Switched from jQuery class functions to plain JavaScript `classList`
- Tested the commit button disabled toggling functionality and it works
as before

---------

Signed-off-by: Yarden Shoham <git@yardenshoham.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Giteabot <teabot@gitea.io>

web_src/js/features/repo-editor.js

@@ -147,8 +147,8 @@ export function initRepoEditor() {
       silent: true,
       dirtyClass: dirtyFileClass,
       fieldSelector: ':input:not(.commit-form-wrapper :input)',
-      change() {
-        const dirty = $(this).hasClass(dirtyFileClass);
+      change($form) {
+        const dirty = $form[0]?.classList.contains(dirtyFileClass);
         commitButton.disabled = !dirty;
       },
     });