Move to the latest ver of Apache Common Math lib

[mpyat2]

As of 08-May-2026, it is 3.6.1 (stable)

[dbenn]

Sounds good @mpyat2. Any particular improvement that caught your attention or mostly stability of version?

[mpyat2]

Hi @dbenn , it seems that there are some improvements in OLSMultipleLinearRegression (I use it in DFTandSpectralWindow.java): https://commons.apache.org/proper/commons-math/changes-report.html