GEODE-10467: Update examples version

Now that support/2.0 has been created,
pair develop examples with 2.1.0

Author: JinwooHwang

gradle.properties

@@ -17,8 +17,8 @@
 
 # Develop to use latest 1.15.1 artifacts until CI is rebuilt
 # GEODE-10436
-version = 1.15.1-build.0
-geodeVersion = 1.15.+
+version = 2.1.0-build.0
+geodeVersion = 2.1.+
 
 # release properties, set these on the command line to validate against
 # a release candidate