Add `.noise_bandwidth()` filter methods

[mhostetter]

• Fixes #399

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 64.28571% with 5 lines in your changes missing coverage. Please review.

Project coverage is 81.42%. Comparing base (801caa7) to head (4b9c09b).

Files	Patch %	Lines
src/sdr/_filter/_iir.py	28.57%	5 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release/0.0.x #419 +/- ## ================================================= - Coverage 81.49% 81.42% -0.07% ================================================= Files 63 63 Lines 3771 3785 +14 ================================================= + Hits 3073 3082 +9 - Misses 698 703 +5 ```

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