Bump the kokoro runner version to v2.1.1.

Author: Jeff Verkoeyen

.kokoro

@@ -9,7 +9,7 @@ fi
 
 pushd .kokoro-ios-runner
 git fetch > /dev/null
-git checkout v2.1.0 > /dev/null
+git checkout v2.1.1 > /dev/null
 popd
 
 ./.kokoro-ios-runner/bazel.sh //:CatalogByConvention