fix: make environment copyable including current state

[BeFranke]

Description

Adds a __deepcopy__ Method to builder.py, making it possible to clone an environment including its current state by simply deepcopy(env)

Motivation and Context

For some use cases, backing up the current state or branching off is desireable.
closes #95

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Types of changes

What types of changes does your code introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds core functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation (update in the documentation)

Checklist

Go over all the following points, and put an x in all the boxes that apply.
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• I have read the CONTRIBUTION guide. (required)
• My change requires a change to the documentation.
• I have updated the tests accordingly. (required for a bug fix or a new feature)
• I have updated the documentation accordingly.
• I have reformatted the code using make format. (required) <- make format crashes on my end, help would be appreciated
• I have checked the code using make lint. (required) <- reformatting not possible, see above. I did my best to sort imports and fix linting errors manually.
• I have ensured make test pass. (required)

[Gaiejj]

LGTM.

The merge-base changed after approval.

[Gaiejj]

LGTM.

[muchvo]

Thank you for your contribution. The code has been merged into the main branch.