feat: add demo trading support (#1610)

* update gitignore

* bump version

* feat: add demo trading support

* update url

* add futures helper methods

* update conf test

* fix missing url

* 8911

* rm proxy none

* update ws_futures_demo_url

* skip failing test and update options symbol

* remove 3.7

* temporarly only test 3.12

* add several fixes including parallel testing

* fix failing tests

* run all tox versions

* update proxy on github action

* add timeout

* fix ws proxy

* add proxy fix for async ws client

* add fix for for options tests

* fix failing tests

* fix lint

* run all tox versions

* add max parallel to 1

* skip ws proxy for py37

* comment options test for py37

* remove 3.7

* increase max parallel to 2

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Co-authored-by: Pablo <pablo@criadoperez.com>