Remove unnecessary cast of kwargs

The intent here was to pass in what might be kwargs if the keyword
flag was set, indicating that kwargs were being passed in. This
assumption XXX

core/src/main/java/org/jruby/RubyTime.java

@@ -1720,7 +1720,7 @@ public IRubyObject initialize(ThreadContext context, IRubyObject[] args) {
 
         int argc = args.length;
         if (keywords) {
-            IRubyObject in = ArgsUtil.extractKeywordArg(context, (RubyHash) args[argc - 1], "in");
+            IRubyObject in = ArgsUtil.extractKeywordArg(context, args[argc - 1], "in");
             if (in != null && argc > 7) {
                 throw context.runtime.newArgumentError("timezone argument given as positional and keyword arguments");
             }