ROOT's TGeoTrack got deprecated

[ChristianTackeGSI]

ROOT 6.26 finally got a notice that TGeoTrack got deprecated.

• https://root.cern.ch/doc/v626/classTGeoTrack.html
• https://root.cern/doc/v626/release-notes.html#class-reference-guide

We should investigate migration options!

[github-actions]

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