Update Font Awesome from 6.5.1 to 6.5.2. (#901)

### Prerequisites

Put an `x` into the box(es) that apply:

- [ ] This pull request fixes a bug.
- [x] This pull request adds a feature.
- [ ] This pull request introduces breaking change.

### Description

This PR updates the version of Font Awesome used within the project from
6.5.1 Free to 6.5.2 Free. This adds additional characters.

The files are directly copied out of the published archive file with no
alterations.

Please note that the CSS regeneration also seems to have pulled in the
mastodon SCSS originally added in #885 - it looks like nobody
regenerated the CSS during that PR. For what it's worth, a while back I
did make a comment #864 about the fact that I have fully automated the
CSS regeneration for my own branch using a Github action. You may want
to consider it too (by which I mean 'tell me if you want it contributed
back').

### Issues Resolved

None

### Checklist

Put an `x` into the box(es) that apply:

#### General

- [x] Describe what changes are being made
- [x] Explain why and how the changes were necessary and implemented
respectively
- [ ] Reference issue with `#<ISSUE_NO>` if applicable

#### Resources

- [x] If you have changed any SCSS code, run `make release` to
regenerate all CSS files

#### Contributors

- [x] Add yourself to `CONTRIBUTORS.md` if you aren't on it already