i forgot about gemoji (#973)

[![PR App][icn]][demo] | Fix RM-XYZ
:-------------------:|:----------:

## 🧰 Changes

Updates Gemoji for new Font Awesome classes

No good:
```.fa.fa-house``` 

Now good:
```.fa-regular.fa-house```

## 🧬 QA & Testing

- [Broken on production][prod].
- [Working in this PR app][demo].


[demo]: https://markdown-pr-PR_NUMBER.herokuapp.com
[prod]: https://SUBDOMAIN.readme.io
[icn]:
https://user-images.githubusercontent.com/886627/160426047-1bee9488-305a-4145-bb2b-09d8b757d38a.svg

Author: runnabro

__tests__/browser/__image_snapshots__/markdown-test-js-visual-regression-tests-rdmd-syntax-renders-code-blocks-without-surprises-2-snap.png

@@ -45,7 +45,7 @@ describe('gemoji parser', () => {
           "hName": "i",
           "hProperties": {
             "className": [
-              "fa",
+              "fa-regular",
               "fa-lock",
             ],
           },

__tests__/parsers/gemoji.test.ts

@@ -24,7 +24,7 @@ const gemojiReplacer = (_, name: string) => {
         data: {
           hName: 'i',
           hProperties: {
-            className: ['fa', name],
+            className: ['fa-regular', name],
           },
         },
       };