Update end to end tests to use java library version 3.1.0 (#745)

Author: kamperiadis

endtoendtests/pom.xml

@@ -22,7 +22,7 @@
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<java.version>1.8</java.version>
 		<azure.functions.maven.plugin.version>1.18.0</azure.functions.maven.plugin.version>
-		<azure.functions.java.library.version>3.0.0-SNAPSHOT</azure.functions.java.library.version>
+		<azure.functions.java.library.version>3.1.0</azure.functions.java.library.version>
 		<durabletask.azure.functions>1.0.0-beta.1</durabletask.azure.functions>
 		<functionAppName>azure-functions-java-endtoendtests</functionAppName>
 		<functionAppRegion>westus</functionAppRegion>