Bump Android compileSdk to 36 for AndroidX compatibility

[SholaWilliams]

Update android/build.gradle to set compileSdk to 36 and add a CHANGELOG entry noting the SDK bump for AndroidX compatibility. This ensures the library targets API 36 for improved AndroidX support.

What does this pull request do?

Bumps the Android compileSdk from 35 to 36. This resolves a build failure when a Flutter app uses compileSdk = 36 and includes this plugin.

What is the motivation and context behind this change?

When a Flutter app uses compileSdk = 36, the plugin fails to build with:
Dependency ':flutter_plugin_android_lifecycle' requires compiling against API 36, but :mapbox_maps_flutter is compiled against 35.

Why this is safe

compileSdk only affects compilation – not runtime behavior or device compatibility. The plugin does not use any API 36 features.

Testing

• I tested this change in my own Flutter app (using the plugin via local path override) – the build succeeded.
• I attempted to build the example app, but it depends on Mapbox SNAPSHOT builds that require authentication (401 Unauthorized). That pre‑existing issue is unrelated to my change.
• The change is minimal and mirrors the previous bump from 33→35 done by the maintainers.

Pull request checklist:

• Updated CHANGELOG.md under ### main
• Commit prefixed with [sdk]

Fixes #1130

[CLAassistant]

All committers have signed the CLA.