Emits deprecation warnings when building with Ruby 3.4

[jirutka]

src/ruby/nxt_ruby_stream_io.c: In function 'nxt_ruby_stream_io_new':
src/ruby/nxt_ruby_stream_io.c:76:5: error: 'rb_data_object_wrap_warning' is deprecated: by TypedData [-Werror=deprecated-declarations]
   76 |     self = Data_Wrap_Struct(class, 0, 0, (void *) (uintptr_t) arg);
      |     ^~~~
In file included from /usr/include/ruby-3.4.0/ruby/internal/core.h:27,
                 from /usr/include/ruby-3.4.0/ruby/ruby.h:29,
                 from /usr/include/ruby-3.4.0/ruby.h:38,
                 from src/ruby/nxt_ruby.h:11,
                 from src/ruby/nxt_ruby_stream_io.c:7:
/usr/include/ruby-3.4.0/ruby/internal/core/rdata.h:293:1: note: declared here
  293 | rb_data_object_wrap_warning(VALUE klass, void *ptr, RUBY_DATA_FUNC mark, RUBY_DATA_FUNC free)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
src/ruby/nxt_ruby_stream_io.c: In function 'nxt_ruby_stream_io_gets':
src/ruby/nxt_ruby_stream_io.c:99:5: error: 'rb_data_object_get_warning' is deprecated: by TypedData [-Werror=deprecated-declarations]
   99 |     Data_Get_Struct(obj, nxt_ruby_ctx_t, rctx);
      |     ^~~~~~~~~~~~~~~
/usr/include/ruby-3.4.0/ruby/internal/core/rdata.h:325:1: note: declared here
  325 | rb_data_object_get_warning(VALUE obj)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
src/ruby/nxt_ruby_stream_io.c: In function 'nxt_ruby_stream_io_read':
src/ruby/nxt_ruby_stream_io.c:155:5: error: 'rb_data_object_get_warning' is deprecated: by TypedData [-Werror=deprecated-declarations]
  155 |     Data_Get_Struct(obj, nxt_ruby_ctx_t, rctx);
      |     ^~~~~~~~~~~~~~~
/usr/include/ruby-3.4.0/ruby/internal/core/rdata.h:325:1: note: declared here
  325 | rb_data_object_get_warning(VALUE obj)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
src/ruby/nxt_ruby_stream_io.c: In function 'nxt_ruby_stream_io_puts':
src/ruby/nxt_ruby_stream_io.c:211:5: error: 'rb_data_object_get_warning' is deprecated: by TypedData [-Werror=deprecated-declarations]
  211 |     Data_Get_Struct(obj, nxt_ruby_ctx_t, rctx);
      |     ^~~~~~~~~~~~~~~
/usr/include/ruby-3.4.0/ruby/internal/core/rdata.h:325:1: note: declared here
  325 | rb_data_object_get_warning(VALUE obj)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
src/ruby/nxt_ruby_stream_io.c: In function 'nxt_ruby_stream_io_write':
src/ruby/nxt_ruby_stream_io.c:229:5: error: 'rb_data_object_get_warning' is deprecated: by TypedData [-Werror=deprecated-declarations]
  229 |     Data_Get_Struct(obj, nxt_ruby_ctx_t, rctx);
      |     ^~~~~~~~~~~~~~~
/usr/include/ruby-3.4.0/ruby/internal/core/rdata.h:325:1: note: declared here
  325 | rb_data_object_get_warning(VALUE obj)
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
make: *** [build/Makefile:2571: build/src/ruby/nxt_ruby_stream_io-ruby.o] Error 1

See https://bugs.ruby-lang.org/issues/19998