[ruby/stringio] Bump version to 3.0.4

https://github.com/ruby/stringio/commit/aeb7e1a0bd
2022-12-05 17:01:57 +09:00 · 2022-12-05 17:01:57 +09:00 · 95e272baf8
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@ -12,7 +12,7 @@

 **********************************************************************/

-#define STRINGIO_VERSION "3.0.3"
+#define STRINGIO_VERSION "3.0.4"

 #include "ruby.h"
 #include "ruby/io.h"