Fix mysql test failure to deprecated to_s(:db) method

Loading development environment (Rails 7.0.8.4)
[1] pry(main)> t = Time.current
=> Thu, 25 Jul 2024 16:56:41.434382638 AEST +10:00
[2] pry(main)>
[3] pry(main)> t.to_s(:db)
DEPRECATION WARNING: TimeWithZone#to_s(:db) is deprecated. Please use TimeWithZone#to_fs(:db) instead. (called from require at bin/rails:4)
=> "2024-07-25 06:56:41"

Author: JesseChavez

test/db/mysql/simple_test.rb

@@ -24,7 +24,9 @@ def test_time_usec_formatting_when_saved_into_string_column
     e = DbType.create!(:sample_string => '', :sample_text => '')
     t = Time.now
     value = Time.local(t.year, t.month, t.day, t.hour, t.min, t.sec, 0)
-    if ActiveRecord::VERSION::MAJOR >= 3
+    if ActiveRecord::VERSION::MAJOR >= 7
+      str = value.utc.to_fs(:db)
+    elsif ActiveRecord::VERSION::MAJOR >= 3
       str = value.utc.to_s(:db)
     else # AR-2.x #quoted_date did not do TZ conversions
       str = value.to_s(:db)