target run included in neighbours

[LukasNickel]

If I am not mistaken, the target run should be included in the list of neighbour runs.
At least I don't see where it is excluded.

In that case this addition:

pybkgmodel/src/pybkgmodel/model.py

Line 49 in 7530cf6

for run in (target_run,) + neighbours

leads to it contributing twice to the background model.