Merge pull request #2207 from ruby/time-xmlschema

`Time#xmlschema` accepts `Integer` argument

Author: soutaro

core/time.rbs

@@ -1629,7 +1629,7 @@ class Time < Object
   #
   # You must require 'time' to use this method.
   #
-  def xmlschema: () -> String
+  def xmlschema: (?Integer fraction_digits) -> String
 
   # <!--
   #   rdoc-file=time.c

test/stdlib/Time_test.rb

@@ -355,10 +355,10 @@ def test_to_a
   end
 
   def test_xmlschema
-    if_ruby("3.4.0"...) do
-      assert_send_type "() -> String",
-                      Time.now, :xmlschema
-    end
+    assert_send_type "() -> String",
+                    Time.now, :xmlschema
+    assert_send_type "(Integer) -> String",
+                    Time.now, :xmlschema, 3
   end
 
   def test_zone