Merge pull request #774 from deckerst/agp8-compat-flutter

[Flutter] AGP8 compatibility

flutter/flutter/android/build.gradle

@@ -19,6 +19,11 @@ rootProject.allprojects {
 apply plugin: 'com.android.library'
 
 android {
+    // Conditional for compatibility with AGP <4.2.
+    if (project.android.hasProperty("namespace")) {
+        namespace 'com.arthenica.ffmpegkit.flutter'
+    }
+
     compileSdkVersion 31
 
     defaultConfig {