Merge some updates from SEA feature branch

[aromanielloNTIA]

This merges a few minor changes that have been made on the nasctn-sea branch, but that are not necessarily specific to SEA.

• Minor change to pyproject.toml which handles testing dependencies as a subset of dev dependencies
• Allow SigMF "captures" to be created with starting sample indices other than 0 (but retain default behavior of starting at 0)
• Allow signal_processing.power_analysis.apply_power_detector to apply statistical power detectors across a parameterized axis, increasing its generality
• Increment version to 4.0.2: main motivation for this is to get the axis change merged into a new release so it can be used by other packages as soon as possible.

[jhazentia]

Looks good to me!