Skip runtime block generator test on 3.4-dev

Author: soutaro

test/rbs/runtime_prototype_test.rb

@@ -389,7 +389,7 @@ def initialize: () -> void
     end
   end
 
-  if RUBY_VERSION >= '3.1'
+  if RUBY_VERSION >= '3.1' && RUBY_VERSION <= "3.3"
     class TestForYield
       def m1() yield end
       def m2() yield 42 end