gtk3: fix a wrong type warning

    compiling rb-gtk3-spin-button.c
    rb-gtk3-spin-button.c:70:15: warning: incompatible function pointer types passing 'VALUE (VALUE)' (aka 'unsigned long (unsigned long)') to parameter of type 'VALUE (*)(VALUE, VALUE)' (aka 'unsigned long (*)(unsigned long, unsigned long)') [-Wincompatible-function-pointer-types]
                  rb_gtk3_spin_button_input_rescue, (VALUE)&input_data);
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /Users/runner/hostedtoolcache/Ruby/3.2.2/x64/include/ruby-3.2.0/ruby/internal/iterator.h:364:62: note: passing argument to parameter 'r_proc' here
    VALUE rb_rescue(VALUE (*b_proc)(VALUE), VALUE data1, VALUE (*r_proc)(VALUE, VALUE), VALUE data2);
                                                                 ^

Reported by MATSUMOTO Katsuyoshi. Thanks!!!

gtk3/ext/gtk3/rb-gtk3-spin-button.c

@@ -46,7 +46,7 @@ rb_gtk3_spin_button_input_body(VALUE user_data)
 }
 
 static VALUE
-rb_gtk3_spin_button_input_rescue(VALUE user_data)
+rb_gtk3_spin_button_input_rescue(VALUE user_data, VALUE error)
 {
     InputData *input_data = (InputData *)user_data;
     g_value_set_int(input_data->data->return_value, GTK_INPUT_ERROR);