update version to 5.6.4

Author: tibbi

app/build.gradle

@@ -15,8 +15,8 @@ android {
         applicationId "com.simplemobiletools.voicerecorder"
         minSdkVersion 21
         targetSdkVersion 30
-        versionCode 17
-        versionName "5.6.3"
+        versionCode 18
+        versionName "5.6.4"
         setProperty("archivesBaseName", "voice-recorder")
         vectorDrawables.useSupportLibrary = true
     }