docs: add stephendkang as a contributor for test, code (#186)

* docs: update README.md [skip ci]

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

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

.all-contributorsrc

@@ -153,6 +153,16 @@
         "test",
         "doc"
       ]
+    },
+    {
+      "login": "stephendkang",
+      "name": "sdkang",
+      "avatar_url": "https://avatars.githubusercontent.com/u/55116501?v=4",
+      "profile": "http://sdkang.org",
+      "contributions": [
+        "test",
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 7,

README.md

@@ -90,6 +90,7 @@ This project started at the [2018 Electrochemical Society (ECS) Hack Week in Sea
   </tr>
   <tr>
     <td align="center"><a href="https://petermattia.com"><img src="https://avatars.githubusercontent.com/u/29551858?v=4?s=100" width="100px;" alt=""/><br /><sub><b>Peter Attia</b></sub></a><br /><a href="https://github.com/ECSHackWeek/impedance.py/commits?author=petermattia" title="Code">💻</a> <a href="https://github.com/ECSHackWeek/impedance.py/commits?author=petermattia" title="Tests">⚠️</a> <a href="https://github.com/ECSHackWeek/impedance.py/commits?author=petermattia" title="Documentation">📖</a></td>
+    <td align="center"><a href="http://sdkang.org"><img src="https://avatars.githubusercontent.com/u/55116501?v=4?s=100" width="100px;" alt=""/><br /><sub><b>sdkang</b></sub></a><br /><a href="https://github.com/ECSHackWeek/impedance.py/commits?author=stephendkang" title="Tests">⚠️</a> <a href="https://github.com/ECSHackWeek/impedance.py/commits?author=stephendkang" title="Code">💻</a></td>
   </tr>
 </table>