docs: Fix ActiveSupport::TimeWithZone#change example [skip ci]

This Pull Request has been created because the documentation for  `ActiveSupport::TimeWithZone#change` wasn't correct.

The behavior of `:hour` and `:min` is different from the example in the documentation.
I checked with Rails 7.1.3.2 and all digits after nano seconds are 0.

```ruby
t = Time.zone.now   #=> Sat, 20 Apr 2024 14:55:55.688536000 JST +09:00
t.change(hour: 12)  #=> Sat, 20 Apr 2024 12:00:00.000000000 JST +09:00
t.change(min: 30)   #=> Sat, 20 Apr 2024 14:30:00.000000000 JST +09:00
```

Author: Judeeeee

activesupport/lib/active_support/time_with_zone.rb

@@ -375,8 +375,8 @@ def ago(other)
     #
     #   t = Time.zone.now          # => Fri, 14 Apr 2017 11:45:15.116992711 EST -05:00
     #   t.change(year: 2020)       # => Tue, 14 Apr 2020 11:45:15.116992711 EST -05:00
-    #   t.change(hour: 12)         # => Fri, 14 Apr 2017 12:00:00.116992711 EST -05:00
-    #   t.change(min: 30)          # => Fri, 14 Apr 2017 11:30:00.116992711 EST -05:00
+    #   t.change(hour: 12)         # => Fri, 14 Apr 2017 12:00:00.000000000 EST -05:00
+    #   t.change(min: 30)          # => Fri, 14 Apr 2017 11:30:00.000000000 EST -05:00
     #   t.change(offset: "-10:00") # => Fri, 14 Apr 2017 11:45:15.116992711 HST -10:00
     #   t.change(zone: "Hawaii")   # => Fri, 14 Apr 2017 11:45:15.116992711 HST -10:00
     def change(options)