Update musa.is-a.dev CNAME to GitHub Pages

Migrate musa.is-a.dev from Cloudflare Pages to GitHub Pages.

Update CNAME record from portfolio-d1z.pages.dev to
musa-excellence.github.io for GitHub Pages custom domain support.

domains/musa.json

@@ -4,6 +4,6 @@
     "email": "musa@excellence.edu.pk"
   },
   "records": {
-    "CNAME": "portfolio-d1z.pages.dev"
+    "CNAME": "musa-excellence.github.io"
   }
 }