Update dependency io.reactivex.rxjava3:rxjava to v3.1.5

Author: renovate[bot]

app/build.gradle

@@ -96,7 +96,7 @@ dependencies {
     implementation 'com.github.wada811:DataBinding-ktx:6.1.0'
 
     // rx
-    implementation 'io.reactivex.rxjava3:rxjava:3.0.6'
+    implementation 'io.reactivex.rxjava3:rxjava:3.1.5'
     implementation 'io.reactivex.rxjava3:rxandroid:3.0.0'
     implementation 'io.reactivex.rxjava3:rxkotlin:3.0.1'