Fix compilation error

Add missing include statement. Error shows up with FairSoft nov20 and FairRoot v18.4.2. Refs #2036.

Dear @v.friese,

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added CodeOwners label

Which compilation error is fixed by this?

Please check https://cdash.gsi.de/viewBuildError.php?buildid=265494 and/or the commit message.

Dear @f.uhlig, I'm have the same problem on my laptop and this commit doesn't fix the problem for me. You have TFolder object already in the header:

https://git.cbm.gsi.de/computing/cbmroot/-/blob/52dd28f2d0e4ae398baae3c7923ed39f483ecb14/reco/detectors/sts/CbmStsFindTracksQa.h#L144

You are right. Thanks for pointing that out. I thought I did a test on one of the machines but probably I mixed it up. I will close the MR and create a new one where the include statement is in the heaxder.

Adding this include in the header resolves the issue on my laptop

closed