Increase test coverage

[martin-springer]

This pull request adds comprehensive tests to cover error handling paths in the rdtools.analysis_chains module. The new tests ensure that invalid inputs and edge cases are properly validated and raise the expected errors, improving the robustness of the codebase.

Testing Improvements:

• Added tests for error handling in rdtools.analysis_chains, including validation for filter_params and filter_params_aggregated setters, index mismatches in clearsky_rescale, and missing data scenarios for various filters (poa_filter, tcell_filter, hour_angle_filter, clearsky_filter). Also added a test for invalid case values in degradation_timeseries_plot.

• [] Code changes are covered by tests
• [] Code changes have been evaluated for compatibility/integration with TrendAnalysis
• [ ] New functions added to __init__.py
• [ ] API.rst is up to date, along with other sphinx docs pages
• [ ] Example notebooks are rerun and differences in results scrutinized
• Updated changelog

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.79%. Comparing base (81b9b56) to head (31ba512).

Additional details and impacted files

@@                    Coverage Diff                    @@
##           multi_YoY_integration     #486      +/-   ##
=========================================================
+ Coverage                  96.66%   96.79%   +0.12%     
=========================================================
  Files                         12       12              
  Lines                       2340     2340              
=========================================================
+ Hits                        2262     2265       +3     
+ Misses                        78       75       -3     

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