refactor: modernize utils.py with type hints and remove legacy Py2 code

[ayushshukla1807]

This PR modernizes the utils.py module to align with modern Python 3 standards (Python 3.9+ syntax).

Changes:

• Added comprehensive type hints across all functions using from __future__ import annotations.
• Replaced legacy six and urllib imports with standard Python 3 equivalents.
• Removed Python 2 compatibility boilerplate (unicode, basestring checks).
• Standardised function signatures and return types for better IDE support and static analysis.

This refactor reduces technical debt and prepares the utility layer for future enhancements.

[lgelauff]

i see no downsides. possible odd one out is encode_value_to_bytes when it would deal with non-strings

[ayushshukla1807]

For encode_value_to_bytes, it's a safety catch for cases where the input might be an integer or a non-string object that needs to be normalized before processing. Python 3 is much less forgiving than Py2 about implicit conversions, so I'd rather have the check there than a crash in production.