[release] bump version to 5.2.1

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jaeopt

README.md

@@ -32,7 +32,7 @@ repositories {
 }
 
 dependencies {
-	implementation 'com.optimizely.ab:android-sdk:5.2.0'
+	implementation 'com.optimizely.ab:android-sdk:5.2.1'
 }
 ```
 

build.gradle

@@ -97,7 +97,7 @@ ext {
     build_tools_version = "35.0.0"
     min_sdk_version = 21
     target_sdk_version = 35
-    java_core_ver = "4.4.0"
+    java_core_ver = "4.4.1"
     android_logger_ver = "1.3.6"
     jacksonversion= "2.11.2"
     annotations_ver = "1.2.0"