Downgrade Firebase BoM to 33.16.0 and update Kotlin plugin to 1.9.25

Author: anhappdev

flutter/android/app/build.gradle

@@ -98,9 +98,8 @@ dependencies {
     androidTestImplementation 'androidx.test:runner:1.2.0'
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
 
-    // firebase-bom v32.8.1 is required to use minSdkVersion 21
-    // https://firebase.google.com/support/release-notes/android#2024-05-02
-    implementation(platform("com.google.firebase:firebase-bom:34.0.0"))
+    // https://firebase.google.com/support/release-notes/android
+    implementation(platform("com.google.firebase:firebase-bom:33.16.0"))
     // When using the BoM, you don't specify versions in Firebase library dependencies
     implementation("com.google.firebase:firebase-appcheck-playintegrity")
     implementation("com.google.firebase:firebase-appcheck-debug")

flutter/android/settings.gradle

@@ -19,7 +19,7 @@ pluginManagement {
 plugins {
     id "dev.flutter.flutter-plugin-loader" version "1.0.0"
     id "com.android.application" version "8.1.4" apply false
-    id "org.jetbrains.kotlin.android" version "1.7.10" apply false
+    id "org.jetbrains.kotlin.android" version "1.9.25" apply false
     id "com.google.gms.google-services" version "4.4.3" apply false
     id "com.google.firebase.crashlytics" version "3.0.5" apply false
 }