Bump leakcanary-android from 2.8.1 to 2.9.1

Bumps [leakcanary-android](https://github.com/square/leakcanary) from 2.8.1 to 2.9.1.
- [Release notes](https://github.com/square/leakcanary/releases)
- [Changelog](https://github.com/square/leakcanary/blob/main/docs/changelog.md)
- [Commits](square/leakcanary@v2.8.1...v2.9.1)

---
updated-dependencies:
- dependency-name: com.squareup.leakcanary:leakcanary-android
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

WooCommerce/build.gradle

@@ -265,7 +265,7 @@ dependencies {
         // See https://github.com/wordpress-mobile/WordPress-FluxC-Android/issues/919
         exclude group: 'com.squareup.okhttp3'
     }
-    debugImplementation 'com.squareup.leakcanary:leakcanary-android:2.8.1'
+    debugImplementation 'com.squareup.leakcanary:leakcanary-android:2.9.1'
 
     // Dependencies for local unit tests
     testImplementation "junit:junit:$jUnitVersion"