Add pyproject.toml for settings

[kotamanegi]

This PR adds pyproject.toml for storing settings. pyproject.toml contains:

• flake8 config
• requirements.txt dependencies information
• setup.py

self-introduction: I'm maintaining Qulacs at Osaka University. QuantestPy seems like a good realistic idea (and I want to contribute to this project!)

[junnaka51]

@mitz1012 @kotamanegi Github actions does not start... 😕 Any suggestions?

[kotamanegi]

I believe @mitz1012 have a right to give permission of running GitHub Actions for first-time contributer (like @junnaka51 and @kotamanegi). This was introduced in 2021/04 because actions were being hacked to execute Bitcoin mining on other people's money.

[mitz1012]

@kotamanegi 申し訳ございませんがCIが動かないため、もう一度pull requestを作り直していただくことは可能でしょうか。 その際に、conflictが発生すると思うので併せてご対応いただけますと幸いです。