Update Rails to 7.0.8.4

What does this MR do and why?

Updates Rails to the latest version!

Changelog: Rails 7.0.8.4 has been released!

These are security releases, so please upgrade at your earliest convenience.

Here is a list of security issues that these releases address:

• CVE-2024-32464 ActionText ContentAttachment’s can Contain Unsanitized HTML
• CVE-2024-28103 Permissions-Policy is Only Served on HTML Content-Type

Here are the shasums for the released gems:

1d6420b32e4289f287c2a83f9633488f8e3bd274  activestorage-7.0.8.4.gem
373857bcd9df9837987905af207cbf6069d8b8d5  actionpack-7.0.8.4.gem
404022a5b8a2d727594cd892deda70582edc3346  railties-7.0.8.4.gem
4239cbde52efd832e1188b8d7ade4da9bd7763a2  actioncable-7.0.8.4.gem
952c861d88b1bf83d75ba836c5ec16976c62adc7  rails-7.0.8.4.gem
954de6662ebce3679fcf7761c7fbb8431f5b8670  actionview-7.0.8.4.gem
a64711dfdc7b1df8d0de6fcc70e7d35cea413d55  activesupport-7.0.8.4.gem
aee5af413ef20f7a3c86e2a662770d75dde0ac0f  actionmailer-7.0.8.4.gem
b27c95a833bf6b623489e9889a8e54a6ef8c01db  activerecord-7.0.8.4.gem
c2221c95322bf40ccf4e3dd0a378859b7de12b74  activejob-7.0.8.4.gem
d07781448737ec5e4ab1e6292b883877934df862  activemodel-7.0.8.4.gem
e04c5fbb0c203f625971ec02435fe4f536c3441b  actiontext-7.0.8.4.gem
e2611a9e05fdbe258bd1c05c21d6479d9fbc22e9  actionmailbox-7.0.8.4.gem

MR acceptance checklist

• This MR is following https://docs.gitlab.com/ee/development/rails_update.html

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.