Fix the expired link of the changelog file. (#5816)

.github/PULL_REQUEST_TEMPLATE

@@ -37,4 +37,4 @@
      ==== 🆕 Remove this line WHEN AND ONLY WHEN you're adding a new feature, follow the checklist 👆 ==== -->
 
 - [ ] If this pull request closes/resolves/fixes an existing issue, replace the issue number. Closes #<issue number>.
-- [ ] Update the [`CHANGES` log](https://github.com/apache/skywalking/blob/c2141978d1039375598a32418b75161a78da22c1/CHANGES.md).
+- [ ] Update the [`CHANGES` log](https://github.com/apache/skywalking/blob/master/CHANGES.md).