Make deepcopy of config before modifying

[TheodoreWolf]

Problem

When initialising a new algo class for a second time, we can get an error due to agent_kwargs being modified in place.

Proposed solution

Add a deepcopy of the config before it is modified by the various algo classes. Also added a basic test case for this.

[keraJLi]

Hi there! First of all, thank you for the pull request on #1.
I appreciate that you added tests for the changes! However, I think a more direct test would be to compare the input dictionary before and after creating the algorithm. Would you be able to change this? Otherwise, I can take care of it at a later date.
Cheers!

[TheodoreWolf]

That makes sense! Will do :)