[DRE-maint] Bug#915837: camping: FTBFS with rails 5.2

[Andrew Lee (=?UTF-8?Q?=E6=9D=8E=E5=81=A5=E7=A7=8B?=)]

Package: camping
Version: 2.1.580-1.1
Severity: important

Dear Maintainer,

I'm help to push rails 5.2 transition for Debian Buster. I tested this
package is FTBFS with rails 5.2 with following error:

```
┌──────────────────────────────────────────────────────────────────────────────┐
│ Run tests for ruby2.5 from debian/ruby-tests.rb                              │
└──────────────────────────────────────────────────────────────────────────────┘

RUBYLIB=/build/camping-2.1.580/debian/camping/usr/lib/ruby/vendor_ruby:. GEM_PATH=debian/camping/usr/share/rubygems-integration/all:/var/lib/gems/2.5.0:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.5.0:/usr/share/rubygems-integration/2.5.0:/usr/share/rubygems-integration/all ruby2.5 debian/ruby-tests.rb
/build/camping-2.1.580/test/app_partials.rb:42: warning: already initialized constant TiltPartials::Controllers::I
<main>:611: warning: previous definition of I was here
/usr/lib/ruby/vendor_ruby/active_record/migration.rb:528:in `inherited': Directly inheriting from ActiveRecord::Migration is not supported. Please specify the Rails release the migration was written for: (StandardError)

  class #<Class:0x000055a07c01a898> < ActiveRecord::Migration[4.2]
	from (eval):25:in `initialize'
	from (eval):25:in `new'
	from (eval):25:in `V'
	from /build/camping-2.1.580/test/apps/migrations.rb:8:in `<module:Models>'
	from /build/camping-2.1.580/test/apps/migrations.rb:6:in `<module:Migrations>'
	from /build/camping-2.1.580/test/apps/migrations.rb:5:in `<top (required)>'
	from /build/camping-2.1.580/test/app_migrations.rb:4:in `load'
	from /build/camping-2.1.580/test/app_migrations.rb:4:in `<top (required)>'
	from /usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
	from /usr/lib/ruby/2.5.0/rubygems/core_ext/kernel_require.rb:59:in `require'
	from debian/ruby-tests.rb:6:in `block in <main>'
	from debian/ruby-tests.rb:6:in `each'
	from debian/ruby-tests.rb:6:in `<main>'
ERROR: Test "ruby2.5" failed. Exiting.
dh_auto_install: dh_ruby --install /build/camping-2.1.580/debian/camping returned exit code 1
make: *** [debian/rules:15: binary] Error 1
dpkg-buildpackage: error: fakeroot debian/rules binary subprocess returned exit status 2
```

I also checked the upstream url. It seems it has been dead for years.

Package has been marked as `Upstream does not support rails 5.2 yet` on:
  https://salsa.debian.org/ruby-team/rails/wikis/Transition-to-Rails-5.2-for-Debian-Buster

Best regards,
-Andrew