Remove support for taint_mode on ruby versions that don't support it

test/integration/drop_test.rb

@@ -114,29 +114,31 @@ class DropsTest < Minitest::Test
     assert_equal('  ', tpl.render!('product' => ProductDrop.new))
   end
 
-  def test_rendering_raises_on_tainted_attr
-    with_taint_mode(:error) do
-      tpl = Liquid::Template.parse('{{ product.user_input }}')
-      assert_raises TaintedError do
-        tpl.render!('product' => ProductDrop.new)
+  if taint_supported?
+    def test_rendering_raises_on_tainted_attr
+      with_taint_mode(:error) do
+        tpl = Liquid::Template.parse('{{ product.user_input }}')
+        assert_raises TaintedError do
+          tpl.render!('product' => ProductDrop.new)
+        end
       end
     end
-  end
 
-  def test_rendering_warns_on_tainted_attr
-    with_taint_mode(:warn) do
-      tpl     = Liquid::Template.parse('{{ product.user_input }}')
-      context = Context.new('product' => ProductDrop.new)
-      tpl.render!(context)
-      assert_equal [Liquid::TaintedError], context.warnings.map(&:class)
-      assert_equal "variable 'product.user_input' is tainted and was not escaped", context.warnings.first.to_s(false)
+    def test_rendering_warns_on_tainted_attr
+      with_taint_mode(:warn) do
+        tpl     = Liquid::Template.parse('{{ product.user_input }}')
+        context = Context.new('product' => ProductDrop.new)
+        tpl.render!(context)
+        assert_equal [Liquid::TaintedError], context.warnings.map(&:class)
+        assert_equal "variable 'product.user_input' is tainted and was not escaped", context.warnings.first.to_s(false)
+      end
     end
-  end
 
-  def test_rendering_doesnt_raise_on_escaped_tainted_attr
-    with_taint_mode(:error) do
-      tpl = Liquid::Template.parse('{{ product.user_input | escape }}')
-      tpl.render!('product' => ProductDrop.new)
+    def test_rendering_doesnt_raise_on_escaped_tainted_attr
+      with_taint_mode(:error) do
+        tpl = Liquid::Template.parse('{{ product.user_input | escape }}')
+        tpl.render!('product' => ProductDrop.new)
+      end
     end
   end