docs: add G-Rath as a contributor for code (#643)

Co-authored-by: allcontributors[bot] <46447321+allcontributors[bot]@users.noreply.github.com>

Author: allcontributors[bot]

.all-contributorsrc

@@ -825,6 +825,15 @@
         "code",
         "test"
       ]
+    },
+    {
+      "login": "G-Rath",
+      "name": "Gareth Jones",
+      "avatar_url": "https://avatars.githubusercontent.com/u/3151613?v=4",
+      "profile": "https://github.com/G-Rath",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "repoHost": "https://github.com",

README.md

@@ -1638,6 +1638,7 @@ Thanks goes to these people ([emoji key][emojis]):
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/idanen"><img src="https://avatars.githubusercontent.com/u/1687893?v=4?s=100" width="100px;" alt="Idan Entin"/><br /><sub><b>Idan Entin</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=idanen" title="Code">💻</a> <a href="https://github.com/testing-library/jest-dom/commits?author=idanen" title="Tests">⚠️</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/mibcadet"><img src="https://avatars.githubusercontent.com/u/925500?v=4?s=100" width="100px;" alt="mibcadet"/><br /><sub><b>mibcadet</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=mibcadet" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://silviuaavram.com"><img src="https://avatars.githubusercontent.com/u/11275392?v=4?s=100" width="100px;" alt="Silviu Alexandru Avram"/><br /><sub><b>Silviu Alexandru Avram</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=silviuaavram" title="Code">💻</a> <a href="https://github.com/testing-library/jest-dom/commits?author=silviuaavram" title="Tests">⚠️</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/G-Rath"><img src="https://avatars.githubusercontent.com/u/3151613?v=4?s=100" width="100px;" alt="Gareth Jones"/><br /><sub><b>Gareth Jones</b></sub></a><br /><a href="https://github.com/testing-library/jest-dom/commits?author=G-Rath" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>