fix: increase minSdkVersion from 21 to 23

[kevinhikaruevans]

In the current version, the library is specifying:

    implementation 'androidx.camera:camera-lifecycle:1.5.0'
    implementation 'androidx.camera:camera-camera2:1.5.0'

but in the changelog for these guys, https://developer.android.com/jetpack/androidx/releases/camera,

Moving the default minSdk from API 21 to API 23

If you try compiling an app with minSdk 21, it throws this error:

/home/runner/work/flutter-app/flutter-app/android/app/src/main/AndroidManifest.xml Error:
uses-sdk:minSdkVersion 21 cannot be smaller than version 23 declared in library [androidx.camera:camera-core:1.5.0] /home/runner/.gradle/caches/8.9/transforms/181faca49283ad7656bf9a10959b799b/transformed/jetified-camera-core-1.5.0/AndroidManifest.xml as the library might be using APIs not available in 21
Suggestion: use a compatible library with a minSdk of at most 21,
or increase this project's minSdk version to at least 23,
or use tools:overrideLibrary="androidx.camera.core" to force usage (may lead to runtime failures)

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':app:processReleaseMainManifest'.
  Manifest merger failed : uses-sdk:minSdkVersion 21 cannot be smaller than version 23 declared in library [androidx.camera:camera-core:1.5.0] /home/runner/.gradle/caches/8.9/transforms/181faca283ad7656bf9a10959b799b/transformed/jetified-camera-core-1.5.0/AndroidManifest.xml as the library might be using APIs not available in 21
  Suggestion: use a compatible library with a minSdk of at most 21,
  or increase this project's minSdk version to at least 23,
  or use tools:overrideLibrary="androidx.camera.core" to force usage (may lead to runtime failures)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 38.14%. Comparing base (1a5fc53) to head (7b87146).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1539      +/-   ##
===========================================
- Coverage    38.24%   38.14%   -0.11%     
===========================================
  Files           42       42              
  Lines          991      991              
===========================================
- Hits           379      378       -1     
- Misses         612      613       +1     

Flag	Coverage Δ
unittests	38.14% <ø> (-0.11%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[navaronbracke]

cc @juliansteenbakker since I think you updated the deps last. This is probably a minor version bump then, and will need a changelog entry also.

[juliansteenbakker]

Flutter min sdk with the latest release is 23, so LGTM!