feat: add `prepost` arg to `Ticker.history` to fetch Pre/Post market data

[loiccoyle]

• add prepost arg to Ticker.history to fetch Pre/Post market data
• add basic testing for prepost arg
• update docs

I had to update the lockfile, as poetry was not letting me install otherwise. I ran poetry lock --no-update.

closes #190

[loiccoyle]

I think CI is failing because it is setup to pull the master branch of pull request forks, this PR is in feat/prepost and not on the master branch, so CI is running into the same issue I was getting when installing which is fixed in this PR.