[clang-tools-extra] [clang-tidy] Correctly ignore function templates in derived-method-shadowing-base-method (#185741) (PR #185875)

[Zeyi Xu via cfe-commits]

https://github.com/zeyi2 requested changes to this pull request.

Sorry for the push back, but the entry in ReleaseNotes should be under `Changes in existing checks`. For example:

```rst
- Improved :doc:`bugprone-derived-method-shadowing-base-method
  <clang-tidy/checks/bugprone/derived-method-shadowing-base-method>` check by 
  correctly ignoring function templates.
```

https://github.com/llvm/llvm-project/pull/185875