Ruby

Fix memory leak of Ractor recv_queue

Memory leak reported:

3   miniruby                              0x104702c1c ractor_init + 164  ractor.c:460
2   miniruby                              0x1046496a0 ruby_xmalloc + 44  gc.c:5188
1   miniruby                              0x10464e840 rb_gc_impl_malloc + 148  default.c:8140
0   libsystem_malloc.dylib                0x19ab3912c _malloc_zone_malloc_instrumented_or_legacy + 152