docs: add stefanv as a contributor for code, design, and review (#49)

* 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

@@ -127,6 +127,17 @@
         "design",
         "review"
       ]
+    },
+    {
+      "login": "stefanv",
+      "name": "Stefan van der Walt",
+      "avatar_url": "https://avatars.githubusercontent.com/u/45071?v=4",
+      "profile": "https://mentat.za.net",
+      "contributions": [
+        "code",
+        "design",
+        "review"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -1,6 +1,6 @@
 # <img src="images/logo/logo.png" width=40 /> pyOpenSci Scientific Python Open Source Packaging Guide
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-12-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-13-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/pyopensci/python-package-guide?color=purple&display_name=tag&style=plastic)
@@ -91,6 +91,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/radoering"><img src="https://avatars.githubusercontent.com/u/30527984?v=4?s=100" width="100px;" alt="Randy Döring"/><br /><sub><b>Randy Döring</b></sub></a><br /><a href="https://github.com/pyOpenSci/python-package-guide/commits?author=radoering" title="Code">💻</a> <a href="https://github.com/pyOpenSci/python-package-guide/pulls?q=is%3Apr+reviewed-by%3Aradoering" title="Reviewed Pull Requests">👀</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://social.juanlu.space/@astrojuanlu"><img src="https://avatars.githubusercontent.com/u/316517?v=4?s=100" width="100px;" alt="Juan Luis Cano Rodríguez"/><br /><sub><b>Juan Luis Cano Rodríguez</b></sub></a><br /><a href="https://github.com/pyOpenSci/python-package-guide/commits?author=astrojuanlu" title="Code">💻</a> <a href="#design-astrojuanlu" title="Design">🎨</a> <a href="https://github.com/pyOpenSci/python-package-guide/pulls?q=is%3Apr+reviewed-by%3Aastrojuanlu" title="Reviewed Pull Requests">👀</a></td>
       <td align="center" valign="top" width="14.28%"><a href="http://iscinumpy.dev"><img src="https://avatars.githubusercontent.com/u/4616906?v=4?s=100" width="100px;" alt="Henry Schreiner"/><br /><sub><b>Henry Schreiner</b></sub></a><br /><a href="https://github.com/pyOpenSci/python-package-guide/commits?author=henryiii" title="Code">💻</a> <a href="#design-henryiii" title="Design">🎨</a> <a href="https://github.com/pyOpenSci/python-package-guide/pulls?q=is%3Apr+reviewed-by%3Ahenryiii" title="Reviewed Pull Requests">👀</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://mentat.za.net"><img src="https://avatars.githubusercontent.com/u/45071?v=4?s=100" width="100px;" alt="Stefan van der Walt"/><br /><sub><b>Stefan van der Walt</b></sub></a><br /><a href="https://github.com/pyOpenSci/python-package-guide/commits?author=stefanv" title="Code">💻</a> <a href="#design-stefanv" title="Design">🎨</a> <a href="https://github.com/pyOpenSci/python-package-guide/pulls?q=is%3Apr+reviewed-by%3Astefanv" title="Reviewed Pull Requests">👀</a></td>
     </tr>
   </tbody>
 </table>