Ignore new ROOT error message about TH1 nbins <=0

When we switched to ROOT 5.34.17 a new warning message appeared
when TH1 is passed nbins <= 0. Since ROOT already sets the value
to nbins=1 we can ignore this warning.
Merge pull request #2757 from Dr15Jones/ignoreNBinsZero

Ignore new ROOT error message about TH1 nbins <=0