chore(deps): update Android SDK to v8.21.1

[github-actions]

Bumps packages/flutter/scripts/update-android.sh from 8.20.0 to 8.21.1.

Auto-generated by a dependency updater.

Changelog

8.21.1

Fixes

• Use Kotlin stdlib 1.9.24 dependency instead of 2.2.0 for all Android modules (#4707)
  • This fixes compile time issues if your app is using Kotlin < 2.x

8.21.0

Fixes

• Only set log template for logging integrations if formatted message differs from template (#4682)

Features

• Add support for Spring Boot 4 and Spring 7 (#4601)
  • NOTE: Our sentry-opentelemetry-agentless-spring is not working yet for Spring Boot 4. Please use sentry-opentelemetry-agent until OpenTelemetry has support for Spring Boot 4.
• Replace UUIDGenerator implementation with Apache licensed code (#4662)
• Replace Random implementation with MIT licensed code (#4664)
• Add support for vars attribute in SentryStackFrame (#4686)
  • Breaking change: The type of the vars attribute has been changed from Map<String, String> to Map<String, Object>.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.36%. Comparing base (a6fd71c) to head (d822c2b).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3243      +/-   ##
==========================================
+ Coverage   87.82%   89.36%   +1.53%     
==========================================
  Files         290       95     -195     
  Lines        9987     3393    -6594     
==========================================
- Hits         8771     3032    -5739     
+ Misses       1216      361     -855     

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