SFMono-Regular is not recognized by Firefox, uses the standard name "SF Mono" (#990)

### Prerequisites

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

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

### Description

SFMono-Regular is not recognized by Firefox, uses the standard name "SF
Mono".

### Issues Resolved

List any existing issues this pull request resolves.

### 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
- [x] 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

---------

Co-authored-by: Luiz F. A. de Prá <luizdepra@users.noreply.github.com>

Author: dantezhu

CONTRIBUTORS.md

@@ -148,4 +148,5 @@
 -   [Matt Ellery](https://github.com/matt-ellery)
 -   [Daniel Olshansky](https://github.com/olshansk)
 -   [Gregor Podjed](https://github.com/gragorther)
+-   [dantezhu](https://github.com/dantezhu)
 -   [Alexander Lazarević](https://e11bits.com)

assets/scss/_variables.scss

@@ -15,7 +15,7 @@ STXihei,"华文细黑",
 SimSun,"宋体",
 Heiti,"黑体",
 sans-serif;
-$code-font-family: SFMono-Regular,
+$code-font-family: "SF Mono",
 Consolas,
 Liberation Mono,
 Menlo,

resources/_gen/assets/scss/coder.scss_3309bf5eef245954e39c3edadcf84268.content

@@ -1 +1 @@
-{"Target":"css/coder.min.6445a802b9389c9660e1b07b724dcf5718b1065ed2d71b4eeaf981cc7cc5fc46.css","MediaType":"text/css","Data":{"Integrity":"sha256-ZEWoArk4nJZg4bB7ck3PVxixBl7S1xtO6vmBzHzF/EY="}}
+{"Target":"css/coder.min.f6b1b35a7b02521b25338f6cf58975f9980a6c12847763fe35a48307758cd1e7.css","MediaType":"text/css","Data":{"Integrity":"sha256-9rGzWnsCUhslM49s9Yl1+ZgKbBKEd2P+NaSDB3WM0ec="}}