Bump external/xamarin-android-tools from 137ad81 to 3debf8e

Bumps [external/xamarin-android-tools](https://github.com/xamarin/xamarin-android-tools) from `137ad81` to `3debf8e`.
- [Commits](dotnet/android-tools@137ad81...3debf8e)

---
updated-dependencies:
- dependency-name: external/xamarin-android-tools
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]