fix(android): Update sentry-android-gradle-plugin to 6.0.0-beta1

Update the minimum required version from 6.0.0-alpha.6 to 6.0.0-beta1 in the size analysis upload documentation.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: runningcode

includes/size-analysis/upload-gradle.mdx

@@ -1,6 +1,6 @@
 The Gradle plugin automatically detects build metadata from your git repository. On GitHub Actions, all metadata is automatically detected. On other CI systems, you may need to manually set some values using the [`vcsInfo`](https://developer.android.com/reference/tools/gradle-api/8.8/com/android/build/api/dsl/VcsInfo) extension.
 
-1. Configure the [Sentry Android Gradle plugin](/platforms/android/configuration/gradle/) with at least version `6.0.0-alpha.6`
+1. Configure the [Sentry Android Gradle plugin](/platforms/android/configuration/gradle/) with at least version `6.0.0-beta1`
 
 2. Set the auth token as an environment variable to be used when running your release build.