[Update] Fix some problems and enhance performance.

android/build.gradle

@@ -52,5 +52,5 @@ android {
 dependencies {
     // 本地依赖，现将aar复制到libs/io/openim/core-sdk/0.0.1/ 下，命名core-sdk-0.0.1.aar
 //    implementation 'io.openim:core-sdk:0.0.1@aar'
-    implementation 'io.openim:core-sdk:3.0.1+1@aar'
+    implementation 'io.openim:core-sdk:3.1.0@aar'
 }

ios/flutter_openim_sdk.podspec

@@ -17,7 +17,7 @@ A new Flutter project.
   s.dependency 'Flutter'
   s.platform = :ios, '11.0'
 
-  s.dependency 'OpenIMSDKCore','3.0.1'
+  s.dependency 'OpenIMSDKCore','3.1.0'
   s.static_framework = true
   # s.vendored_frameworks = 'Framework/*.framework'
   # Flutter.framework does not contain a i386 slice.