Update FiraCode to v3.1

[iamolivinius]

Description

Please explain the changes you made here.

Requirements / Checklist

• Read the Contributing Guidelines
• Read or at least glanced at the FAQ
• Read or at least glanced at the Wiki
• Scripts execute without error (if necessary):
  • If any of the scripts were modified they have been tested and execute without error, e.g.:
    • ./font-patcher Inconsolata.otf --fontawesome --octicons --pomicons
    • ./gotta-patch-em-all-font-patcher\!.sh Hermit
• Extended the README and documentation if necessary, e.g. You added a new font please update the table

What does this Pull Request (PR) do?

This PR adds patched and unpatched FiraCode v.3.1 files to the repository

How should this be manually tested?

1. Install Fira Code Regular Nerd Font Complete
2. Configure your editor or terminal of choice to use FiraCode Nerd Font
3. Enable ligatures if possible
4. Check if you can see the adjusted combinations in your editor or terminal as they are shown here: https://github.com/tonsky/FiraCode#whats-in-the-box

Any background context you can provide?

What are the relevant tickets (if any)?

Screenshots (if appropriate or helpful)

[byg0n3]

as a follow up on this - FiraCode author released v4 yesterday with some noticeable changes
maybe consider switching to it instead of v3.1?

[felipecrs]

Actually, it's currently on v5.2.

[gitfool]

FWIW, I wanted to learn more about how nerd fonts worked so I created PR #497 with the latest version.

[ryanoasis]

My bad this should've gotten merged in long ago. I'll probably work to get this in and then merge #497 so both will get counted