Replace filterpy package

Describe the bug
Python 3.12 started emitting DeprecationWarning for invalid escape sequences in string literals, and Python 3.13 upgraded those to SyntaxWarning. The filterpy package has a docstring in helpers.py line 367 containing:

P = \Sum {A[i] B[i].T} for i in 0..N

That \S is not a valid Python escape sequence (like \n, \t, etc.), but it was silently ignored in Python ≤3.11. Since our default environment uses Python 3.13, it now triggers a SyntaxWarning at import time.

The filterpy package is unmaintained (last release was 2018), so the fix won't come from upstream.

Full error message and traceback
This is a compile-time warning — it's emitted when Python compiles the .py source file to bytecode (.pyc). On local Windows machine, filterpy was already compiled to .pyc during a prior import (e.g., when pip/pixi installed it, or during a previous notebook run). Since the cached .pyc exists, Python skips recompilation on subsequent imports and the warning is never re-emitted. That's why local saved notebook output doesn't include it.

To Reproduce
Run Github nbval Workflow and remove [regex3] and [regex4] sanitation rules.

Expected behavior
No SyntaxWarning.

Screenshots
If applicable, add screenshots to help explain your problem.

Additional context
The soiling module uses filterpy for Kalman filtering; could switch to a maintained alternative like simdkalman or inline the needed logic

Commit 98907c1a44db5a879edf800c8fc94d897c124ef6 tries to sanitize the Warning from the notebooks.

Start by inspecting the soiling module's use of filterpy and the GitHub nbval workflow under Python 3.13. Review commit 98907c1a44db5a879edf800c8fc94d897c124ef2 to understand the existing regex3 and regex4 sanitation, then determine the required replacement or inline logic. Done means the sanitation rules can be removed and the workflow completes without a SyntaxWarning.