docs: add Yangliu-SY as a contributor for code (#1262)

* docs: update CONTRIBUTING.md [skip ci]

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

---------

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

.all-contributorsrc

@@ -353,6 +353,15 @@
       "contributions": [
         "code"
       ]
+    },
+    {
+      "login": "Yangliu-SY",
+      "name": "Yangliu-SY",
+      "avatar_url": "https://avatars.githubusercontent.com/u/144334404?v=4",
+      "profile": "https://github.com/Yangliu-SY",
+      "contributions": [
+        "code"
+      ]
     }
   ],
   "contributorsPerLine": 7,

CONTRIBUTING.md

@@ -1,6 +1,6 @@
 
 <!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
-[![All Contributors](https://img.shields.io/badge/all_contributors-38-orange.svg?style=flat-square)](#contributors-)
+[![All Contributors](https://img.shields.io/badge/all_contributors-39-orange.svg?style=flat-square)](#contributors-)
 <!-- ALL-CONTRIBUTORS-BADGE:END -->
 
 ## Contributors ✨
@@ -61,6 +61,7 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
       <td align="center" valign="top" width="14.28%"><a href="https://www.linkedin.com/in/rahulbshrestha/"><img src="https://avatars.githubusercontent.com/u/22676591?v=4?s=100" width="100px;" alt="Rahul Shrestha"/><br /><sub><b>Rahul Shrestha</b></sub></a><br /><a href="https://github.com/py-why/dowhy/commits?author=rahulbshrestha" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/yogabonito"><img src="https://avatars.githubusercontent.com/u/7026269?v=4?s=100" width="100px;" alt="yogabonito"/><br /><sub><b>yogabonito</b></sub></a><br /><a href="https://github.com/py-why/dowhy/commits?author=yogabonito" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/nparent1"><img src="https://avatars.githubusercontent.com/u/52084137?v=4?s=100" width="100px;" alt="Nick Parente"/><br /><sub><b>Nick Parente</b></sub></a><br /><a href="https://github.com/py-why/dowhy/commits?author=nparent1" title="Code">💻</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/Yangliu-SY"><img src="https://avatars.githubusercontent.com/u/144334404?v=4?s=100" width="100px;" alt="Yangliu-SY"/><br /><sub><b>Yangliu-SY</b></sub></a><br /><a href="https://github.com/py-why/dowhy/commits?author=Yangliu-SY" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>