Update RxJava to 3.1.5.

Author: Isira-Seneviratne

app/build.gradle

@@ -265,7 +265,7 @@ dependencies {
     implementation 'com.jakewharton:process-phoenix:2.1.2'
 
     // Reactive extensions for Java VM
-    implementation "io.reactivex.rxjava3:rxjava:3.0.13"
+    implementation "io.reactivex.rxjava3:rxjava:3.1.5"
     implementation "io.reactivex.rxjava3:rxandroid:3.0.0"
     // RxJava binding APIs for Android UI widgets
     implementation "com.jakewharton.rxbinding4:rxbinding:4.0.0"