version bump to 2.6.4 + changelog

CHANGELOG.md

 # Changelog
 
+### Version 2.6.4
+
+* Support automatic theme switching on Android 10
+
 ### Version 2.6.3
 
 * Support for ?register and ?register;preauth XMPP uri parameters

build.gradle

@@ -90,8 +90,8 @@ android {
     defaultConfig {
         minSdkVersion 16
         targetSdkVersion 28
-        versionCode 360
-        versionName "2.6.3"
+        versionCode 362
+        versionName "2.6.4"
         archivesBaseName += "-$versionName"
         applicationId "eu.siacs.conversations"
         resValue "string", "applicationId", applicationId