A warning line should look like a warning section

[ci skip]
Fix typo in Active Model guide

- instrospection -> introspection.
- [ci skip]
Merge pull request #17183 from prathamesh-sonpatki/fix-typo-in-am-guide

Fix typo in Active Model guide
fix autoload tests
unify PG spelling in CHANGELOGs. [ci skip]
Change `gsub` to `tr` where possible
update queue_classic details
Merge pull request #17189 from jipiboily/update-queue-classic-details

update queue_classic details [ci skip]
speed up fixtures by not loading all their classes
Rephrasing sentences
Merge pull request #17146 from divineforest/active-record-gsub-to-tr

Change `gsub` to `tr` where possible
Merge pull request #17184 from fillman/master

fix autoload tests
Merge pull request #17198 from neerajdotname/wordsmitthing

Rephrasing sentences
Fix grammar
Merge pull request #17201 from djpowers/patch-1

Fix grammar [ci skip]
remove un-needed sort

HTML doesn't care what order the elements are rendered in, so why should we?

Updates tests to use proper `assert_dom_equal` instead of `assert_equal` /cc @jeremy
Merge pull request #17203 from schneems/schneems/av-tag_helper

remove un-needed sort
fix tests on action_mailer

Include appropriate helpers and use `assert_dom_equal` where applicable
Merge pull request #17204 from schneems/schneems/fix-am-tests-master

fix tests on action_mailer
Only include the needed assertions