Update alpha_bug_report.yaml

.github/ISSUE_TEMPLATE/alpha_bug_report.yaml

@@ -1,6 +1,6 @@
 name: "[Alpha Only] Bug Report"
 description: CasaOS Alpha Testing specific bug report form.
-title: "[Alpha][Bug]: "
+title: "[Alpha][Bug] "
 labels: ["alpha", "bug"]
 body:
   - type: markdown