docs: add G-Rath as a contributor for code, and maintenance (#943)

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

Author: allcontributors[bot]

.all-contributorsrc

@@ -413,7 +413,8 @@
       "contributions": [
         "code",
         "doc",
-        "test"
+        "test",
+        "maintenance"
       ]
     },
     {

README.md

@@ -482,7 +482,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <tr>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/ph-fritsche"><img src="https://avatars.githubusercontent.com/u/39068198?v=4?s=100" width="100px;" alt="Philipp Fritsche"/><br /><sub><b>Philipp Fritsche</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=ph-fritsche" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="http://zaicevas.me"><img src="https://avatars.githubusercontent.com/u/34719980?v=4?s=100" width="100px;" alt="Tomas Zaicevas"/><br /><sub><b>Tomas Zaicevas</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/issues?q=author%3Azaicevas" title="Bug reports">🐛</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=zaicevas" title="Code">💻</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=zaicevas" title="Tests">⚠️</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=zaicevas" title="Documentation">📖</a></td>
-      <td align="center" valign="top" width="14.28%"><a href="/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="/testing-library/eslint-plugin-testing-library/commits?author=G-Rath" title="Code">💻</a> <a href="/testing-library/eslint-plugin-testing-library/commits?author=G-Rath" title="Documentation">📖</a> <a href="/testing-library/eslint-plugin-testing-library/commits?author=G-Rath" title="Tests">⚠️</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="/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="/testing-library/eslint-plugin-testing-library/commits?author=G-Rath" title="Code">💻</a> <a href="/testing-library/eslint-plugin-testing-library/commits?author=G-Rath" title="Documentation">📖</a> <a href="/testing-library/eslint-plugin-testing-library/commits?author=G-Rath" title="Tests">⚠️</a> <a href="#maintenance-G-Rath" title="Maintenance">🚧</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/HonkingGoose"><img src="https://avatars.githubusercontent.com/u/34918129?v=4?s=100" width="100px;" alt="HonkingGoose"/><br /><sub><b>HonkingGoose</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=HonkingGoose" title="Documentation">📖</a> <a href="#maintenance-HonkingGoose" title="Maintenance">🚧</a></td>
       <td align="center" valign="top" width="14.28%"><a href="http://everlong.org/"><img src="https://avatars.githubusercontent.com/u/454175?v=4?s=100" width="100px;" alt="Julien Wajsberg"/><br /><sub><b>Julien Wajsberg</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/issues?q=author%3Ajulienw" title="Bug reports">🐛</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=julienw" title="Code">💻</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=julienw" title="Tests">⚠️</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://www.linkedin.com/in/maratdyatko/"><img src="https://avatars.githubusercontent.com/u/31615495?v=4?s=100" width="100px;" alt="Marat Dyatko"/><br /><sub><b>Marat Dyatko</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/issues?q=author%3Adyatko" title="Bug reports">🐛</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=dyatko" title="Code">💻</a></td>