[tutorials][tmva] Fix a dependency issue with TMVA tutorials

[lmoneta]

Change the name of the file where the tutorial TMVA_SOFIE_RDataFrame.py writes the model, to avoid a conflict with TMVA_SOFIE_RDataFrame.C

[github-actions[bot]]

Test Results

    12 files      12 suites   2d 19h 49m 23s :stopwatch:  2 637 tests  2 636 :white_check_mark: 0 :zzz: 1 :x: 29 952 runs  29 951 :white_check_mark: 0 :zzz: 1 :x:

For more details on these failures, see this check.

Results for commit aa7d79f8.