docs: add Dennis273 as a contributor for code (#1092)

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

.all-contributorsrc

@@ -1506,6 +1506,15 @@
       "contributions": [
         "bug"
       ]
+    },
+    {
+      "login": "Dennis273",
+      "name": "Dennis273",
+      "avatar_url": "https://avatars.githubusercontent.com/u/19815164?v=4",
+      "profile": "https://github.com/Dennis273",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "repoHost": "https://github.com"

README.md

@@ -329,6 +329,9 @@ Thanks goes to these people ([emoji key][emojis]):
     <td align="center"><a href="https://github.com/jrnail23"><img src="https://avatars.githubusercontent.com/u/392612?v=4?s=100" width="100px;" alt=""/><br /><sub><b>James Nail</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/issues?q=author%3Ajrnail23" title="Bug reports">🐛</a></td>
     <td align="center"><a href="https://github.com/robcaldecott"><img src="https://avatars.githubusercontent.com/u/796702?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Rob Caldecott</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/issues?q=author%3Arobcaldecott" title="Bug reports">🐛</a></td>
   </tr>
+  <tr>
+    <td align="center"><a href="https://github.com/Dennis273"><img src="https://avatars.githubusercontent.com/u/19815164?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Dennis273</b></sub></a><br /><a href="https://github.com/testing-library/dom-testing-library/commits?author=Dennis273" title="Code">💻</a></td>
+  </tr>
 </table>
 
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