Upgrade to Rxjava 1.3.7

Closes gh-12616

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -138,7 +138,7 @@
 		<reactor-bom.version>Bismuth-BUILD-SNAPSHOT</reactor-bom.version>
 		<rest-assured.version>3.0.7</rest-assured.version>
 		<reactive-streams.version>1.0.2</reactive-streams.version>
-		<rxjava.version>1.3.6</rxjava.version>
+		<rxjava.version>1.3.7</rxjava.version>
 		<rxjava-adapter.version>1.2.1</rxjava-adapter.version>
 		<rxjava2.version>2.1.10</rxjava2.version>
 		<selenium.version>3.9.1</selenium.version>