docs: add justintoman as a contributor for code, and test (#819)

* docs: update README.md [skip ci]

* docs: update .all-contributorsrc [skip ci]

---------

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

Author: allcontributors[bot]

.all-contributorsrc

@@ -618,6 +618,16 @@
         "code",
         "test"
       ]
+    },
+    {
+      "login": "justintoman",
+      "name": "justintoman",
+      "avatar_url": "https://avatars.githubusercontent.com/u/11649507?v=4",
+      "profile": "https://github.com/justintoman",
+      "contributions": [
+        "code",
+        "test"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -422,6 +422,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
     <tr>
       <td align="center" valign="top" width="14.28%"><a href="https://dale.io"><img src="https://avatars.githubusercontent.com/u/389851?v=4?s=100" width="100px;" alt="Dale Karp"/><br /><sub><b>Dale Karp</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=obsoke" title="Code">💻</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=obsoke" title="Tests">⚠️</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=obsoke" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/nathanmmiller"><img src="https://avatars.githubusercontent.com/u/37555055?v=4?s=100" width="100px;" alt="Nathan"/><br /><sub><b>Nathan</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=nathanmmiller" title="Code">💻</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=nathanmmiller" title="Tests">⚠️</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/justintoman"><img src="https://avatars.githubusercontent.com/u/11649507?v=4?s=100" width="100px;" alt="justintoman"/><br /><sub><b>justintoman</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=justintoman" title="Code">💻</a> <a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=justintoman" title="Tests">⚠️</a></td>
     </tr>
   </tbody>
 </table>