Use assert_in_delta to fix timestamp failure

https://buildkite.com/rails/rails/builds/114641#0193b412-5914-4b04-900e-24343699b6a8/1304-1316

Author: kamipo

activerecord/test/cases/dirty_test.rb

@@ -945,13 +945,11 @@ def check_around
       aircraft = Aircraft.new(name: "Boeing")
       assert_equal "Boeing", aircraft.name
 
-      time_before_saving = Time.now
       aircraft.save!
-      time_after_saving = Time.now
       aircraft.reload
 
       assert_equal "Boeing", aircraft.name
-      assert_includes time_before_saving - 1..time_after_saving + 1, aircraft.manufactured_at
+      assert_in_delta Time.now, aircraft.manufactured_at, 1
     end
   end
 

activerecord/test/cases/fixtures_test.rb

@@ -481,7 +481,7 @@ def test_insert_with_default_function
     create_fixtures("aircrafts")
 
     aircraft = Aircraft.find_by(name: "boeing-with-no-manufactured-at")
-    assert_equal Time.now.utc.strftime("%Y-%m-%d %H:%M:%S"), aircraft.manufactured_at.strftime("%Y-%m-%d %H:%M:%S")
+    assert_in_delta Time.now, aircraft.manufactured_at, 1
   end
 
   def test_insert_with_default_value