Updated to better support nested mappings and dataclasses in log_hyperparameters()

[SiddhantSadangi]

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Pull Request Overview

This PR simplifies the log_hyperparameters() method in the Neptune logger by replacing manual flattening logic with Neptune's built-in flatten=True and cast_unsupported=True parameters. It also updates the minimum version requirement for neptune-scale to 0.18.0.

• Replaces custom dictionary flattening implementation with Neptune's native flattening capability
• Updates neptune-scale minimum version requirement to 0.18.0
• Removes redundant datetime import and custom type handling logic

Comments suppressed due to low confidence (1)

src/lightning/pytorch/loggers/neptune.py:45

• The version constraint neptune-scale>=0.18.0 should be verified to ensure this version exists and supports the flatten and cast_unsupported parameters used in the updated code.

_NEPTUNE_SCALE_AVAILABLE = RequirementCache("neptune-scale>=0.18.0")