vm_args.c: rephrase the warning message of keyword argument separation

(old)
test.rb:4: warning: The last argument is used as the keyword parameter
test.rb:1: warning: for `foo' defined here; maybe ** should be added to the call?

(new)
test.rb:4: warning: The last argument is used as keyword parameters; maybe ** should be added to the call
test.rb:1: warning: The called method `foo' is defined here

1 files changed, 1 insertions, 1 deletions

diff --git a/class.c b/class.c
index 4129647bdc..cceba6a189 100644
--- a/class.c
+++ b/class.c
@@ -2051,7 +2051,7 @@ rb_scan_args_parse(int kw_flag, int argc, const VALUE *argv, const char *fmt, st
                     if (!keyword_given && !last_hash_keyword) {
                         /* Warn if treating positional as keyword, as in Ruby 3,
                            this will be an error */
-                        rb_warn("The last argument is used as the keyword parameter");
+                        rb_warn("The last argument is used as keyword parameters");
                     }
                     argc--;
                 }