Allow booleans on filtering

[oddaspa]

Describe the bug

query.Filter(fields={"visible": True})
{'$and': [{'name': {'$in': ['Electricity price']}}, {'labels.folder-0': 'Trondheim'}, {'visible': 'True'}]}

To Reproduce
Steps to reproduce the behavior:

import pyclarify
...

Expected behavior
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Screenshots
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** System information (please complete the following information):**
OS: (e.g. Windows 10)
Python Version: (e.g. 3.8)
SDK Version: (e.g. 0.2.2)

Additional context
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