Deal with different Ruby versions

spec/ruby/library/bigdecimal/round_spec.rb

@@ -228,7 +228,15 @@ describe "BigDecimal#round" do
     -> { BigDecimal('-Infinity').round(2) }.should_not raise_error(FloatDomainError)
   end
 
-  it "raise for a non-existent round mode" do
-    -> { @p1_50.round(0, :nonsense) }.should raise_error(ArgumentError, "invalid rounding mode (nonsense)")
+  ruby_version_is ''...'3.2' do
+    it 'raise for a non-existent round mode' do
+      -> { @p1_50.round(0, :nonsense) }.should raise_error(ArgumentError, "invalid rounding mode")
+    end
+  end
+
+  ruby_version_is '3.2' do
+    it 'raise for a non-existent round mode' do
+      -> { @p1_50.round(0, :nonsense) }.should raise_error(ArgumentError, "invalid rounding mode (nonsense)")
+    end
   end
 end