docs(contributor): add 7sDream (wechaty#961)

Author: 7sDream

jekyll/_contributors/7sdream.md

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+---
+name: 7sDream
+site: https://7sdre.am/
+avatar: /assets/contributors/7sdream/avatar.png
+bio: Backend engigneer using Golang/NodeJS/C++ in Tencent, Rustaceans in life.
+email: wechaty@7sdre.am
+twitter: https://twitter.com/7sDream
+---
+
+Backend engigneer using Golang/NodeJS/C++ in Tencent, Rustaceans in life.
+
+## Contact
+
+- Homepage: <https://7sdre.am/>
+- Github: <https://github.com/7sDream>
+- Twitter: <https://twitter.com/7sDream>
+- Email: <wechaty@7sdre.am>