docs: add diegocasmo as a contributor for code (#531)

* 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

@@ -463,6 +463,15 @@
       "contributions": [
         "test"
       ]
+    },
+    {
+      "login": "diegocasmo",
+      "name": "Diego Castillo",
+      "avatar_url": "https://avatars.githubusercontent.com/u/4553097?v=4",
+      "profile": "https://diegocasmo.github.io/",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -383,6 +383,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
   </tr>
   <tr>
     <td align="center"><a href="https://codepen.io/ariperkkio/"><img src="https://avatars.githubusercontent.com/u/14806298?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Ari Perkkiö</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=AriPerkkio" title="Tests">⚠️</a></td>
+    <td align="center"><a href="https://diegocasmo.github.io/"><img src="https://avatars.githubusercontent.com/u/4553097?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Diego Castillo</b></sub></a><br /><a href="https://github.com/testing-library/eslint-plugin-testing-library/commits?author=diegocasmo" title="Code">💻</a></td>
   </tr>
 </table>