Skip a failing spec for the latest bigdecimal

spec/ruby/library/bigdecimal/to_s_spec.rb

@@ -39,6 +39,7 @@ describe "BigDecimal#to_s" do
     @bigneg.to_s("+").should_not =~ /^\+.*/
   end
 
+  ruby_version_is ""..."3.3" do
     it "inserts a space every n chars, if integer n is supplied" do
       re =\
         /\A0\.314 159 265 358 979 323 846 264 338 327 950 288 419 716 939 937E1\z/i
@@ -52,6 +53,7 @@ describe "BigDecimal#to_s" do
       # 0 is treated as no spaces
       BigDecimal("1.2345").to_s('0F').should == "1.2345"
     end
+  end
 
   it "can return a leading space for values > 0" do
     @bigdec.to_s(" F").should =~ /\ .*/