Update Font Awesome icons to version 7

[xaviermawet]

Hi,

This pull request updates Font Awesome icons to version 7.
It uses the new fontawesome7 CTAN package, developed by the same author as the previous fontawesome6 package.

[OJFord]

Nice, thanks. Have you checked the icon names? (If I recall correctly quite a few changed between fa5 -> fa6.)

[xaviermawet]

Yes, no name changes have been made to the icons used in your template, at least not at the time I created my pull request. I'll rebase my branch on top of your master branch to incorporate the latest changes and ensure it still builds correctly.

Regards,

[queeno]

I confirm that the icon names haven't changed in fontawesome7
Let's get this merged 👍
Please rebase and solve the conflict @xaviermawet

[xaviermawet]

Hi @OJFord & @queeno,

I rebased my branch on top of your master branch.
I also updated the local build instructions in the README.md + Dockerfile matching your github workflow (needed since the recent font changes).

Regards and happy new year

[xaviermawet]

Would you prefer that I remove my commit related to the build instructions so the PR focuses only on the FontAwesome 7 changes? Would that help speed up the merge? Thanks!