added a custom reward based env in meta/env_stock_trading based on sharpe-ratio and minimum-trades requirement (#354)

* Add files via upload

* Update env_mintrades_stocktrading.py

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: Cpt-Shaan