MAINT: Bootstrap update

Proposed changes

Resolves #132 - updates bootstrap to v5.0.1. Navbar and plotting tabs have been updated to make use of new/renamed classes and variables. Other changes include:

Updated CSS to use only what is needed
Updated col-* classes in index.html to use col-* instead of col-sm-*, which was originally meant for different screen sizes (e.g. mobile vs desktop)
Centered the video within the col-5 on index.html
Font size (which was not previously set), now set to 2.5% of viewport width for navigation headings
Icon sizes in footer updates
Removed figcaption class from CSS, which was never used AFAIK

I have also run `prettier` on the files I have touched, so some of the formatting may have changed from before.

Types of changes

What types of changes does your code introduce? Put an x in the boxes that apply

[ ] Bugfix (non-breaking change which fixes an issue)
[ ] New feature (non-breaking change which adds functionalitiy)
[ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
[x] Other (if none of the other choices apply)

Checklist

Put an x in the boxes that apply. You can also fill these out after creating the PR. If you are unsure about any of the choices, don't hesitate to ask!

[x] Changes have been tested to ensure that fix is effective or that a feature works.
[x] Changes pass the unit tests
[x] Code has been run through black with the -l 79 flag.
[x] I have included necessary documentation or comments (as necessary)
[ ] Any dependent changes have been merged and published

Notes

All PRs will undergo the unit testing before being reviewed. You may be requested to explain or make additional changes before the PR is accepted.

_PR template was adopted from appium_

afids / afids-validator