Update License, Code of Conduct, and README

[ytdHuang]

Summary of this PR:

• Update to same license as qutip and add license badge in README
• Add code of conduct (same as qutip) and also ignore it in JuliaFormatter (since it is also markdown file)
• Add the name list of admin team (and corresponding hyperlinks to their github page)

I find out that when someone wants to contribute (to this package) and make a PR, the list of reviewers includes all the qutip admins. So I thought we can at least do the same thing as qutip: put the admin name list on top of the README.

@albertomercurio, @lgravina1997
What do you think? Is it okay for you guys ?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.12%. Comparing base (6c0f46d) to head (b541e5d).
Report is 5 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #133   +/-   ##
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  Coverage   91.12%   91.12%           
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  Files          21       21           
  Lines        1757     1757           
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  Hits         1601     1601           
  Misses        156      156           

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