This will avoid the branch being deleted by mistake making all builds to
fail.

Queue_classic currently limits pg to "< 0.20".
It is therefore not used for rails CI tests. There has been
a bull request for a while (by a co-worker of mine), which
fixes the incompatibilities and extends dependencies to pg-1.x.

This patch add this pull request to the Gemfile as an interim
solution, until it is merged.

Seems some tests not work with Minitest 5.11.0.

* https://travis-ci.org/rails/rails/jobs/323997512#L1053
* https://travis-ci.org/rails/rails/jobs/323997486#L1055

Ref: https://github.com/seattlerb/minitest/issues/729

Ref: https://github.com/collectiveidea/delayed_job/blob/master/CHANGELOG.md#414---2017-12-29

For pass Active Job integration tests with Ruby 2.5.
Ref: https://github.com/collectiveidea/delayed_job/pull/996

Follow up of #31432.

The v4.3.1 has already released that includes Redis 4.0 support.
https://github.com/resque/resque-scheduler/blob/master/CHANGELOG.md#431---2017-11-20

The `keyfile` was renamed to `credentials` in `google-cloud-storage` 1.8.0.
https://github.com/GoogleCloudPlatform/google-cloud-ruby/blob/master/google-cloud-storage/CHANGELOG.md#180--2017-11-14

Although `keyfile` can still be used, but it looks like deprecate.
https://github.com/GoogleCloudPlatform/google-cloud-ruby/blob/ddf7b2a856d676316525eb581c1a4cc83ca6097b/google-cloud-storage/lib/google/cloud/storage.rb#L589...L590

Therefore, I think that should use `credentials` in newly generated
applications.

Ref: https://github.com/GoogleCloudPlatform/google-cloud-ruby/issues/1802

This reverts commit 536d3068.

`em-hiredis` is unused since 48766e32

Move back to resque-scheduler mainline now that https://github.com/resque/resque-scheduler/pull/620 is merged

The `redis-namespace` 1.6.0 includes redis-rb 4.0 support.

Reverts 4d96be1c
References #31026

```ruby
TestHelperMailerTest#test_encode
BaseTest#test_implicit_multipart_with_attachments_creates_nested_parts
BaseTest#test_implicit_multipart_with_attachments_and_sort_order
BaseTest#test_explicit_multipart_with_attachments_creates_nested_parts
```
Refer https://travis-ci.org/rails/rails/jobs/295571582

This has been added by 8f8cb1ba.
But now it is unnecessary because it is not used in the test.

The sidekiq 5.0.5 includes redis-rb 4.0 support.
Ref: https://github.com/mperham/sidekiq/blob/90db3b84208cbb73a50d1a77a1dea97d3490ce70/Changes.md#505

* Use `gem 'redis', '~> 4.0'` for new app Gemfiles
* Loosen Action Cable redis-rb dep to `>= 3.3, < 5`
* Bump redis-namespace for looser Redis version dep
* Avoid using the underlying `redis.client` directly
* Use `Redis.new` instead of `Redis.connect`

Most interesting to us, 2.4.2 and 2.3.5 include the fix for
https://bugs.ruby-lang.org/issues/13632

`qu-redis` is need for qu adapter test.
However, since 8ecc5ab1, qu adapter test has not been executed,
it is unnecessary now.

I'm not sure this is the problem we're seeing on Travis (occasional
unexpected IOError exceptions), but it's worth a try.

This fork brings:

* A tiny refresh of the default theme.
* SEO tags to class files.
* The removal of HTML tags from search results.
* Some general template clean-up (HTML 5, removal of the jQuery
  effect library, etc.).
* A speed up of the generation time (by ~30 seconds).

thor 0.20.0 was released so we can test with the released version.

Follow up of https://github.com/rails/rails/commit/0b8441bd415c444b8d4afbfc93af79ec7677aa2c

No need to depend on my fork anymore, they've just release fix
officially.

```
% be rubocop -a --only Style/StringLiterals activestorage
Inspecting 74 files
........................................CCCCCCCCCC.C........CC.......C.C..

(snip)

74 files inspected, 31 offenses detected, 31 offenses corrected
```