Merge pull request #567 from square/dependabot/gradle/kotlin/io.reactivex.rxjava2-rxjava-2.2.12

Author: dependabot-preview[bot]

kotlin/build.gradle

@@ -92,7 +92,7 @@ buildscript {
       'detekt': "io.gitlab.arturbosch.detekt:detekt-gradle-plugin:1.0.1",
       'okio': "com.squareup.okio:okio:2.4.0",
       'rxjava2':[
-          'rxjava2': "io.reactivex.rxjava2:rxjava:2.2.11",
+          'rxjava2': "io.reactivex.rxjava2:rxjava:2.2.12",
           'extensions': "com.github.akarnokd:rxjava2-extensions:0.20.10"
       ],
       'annotations': [