update-parent in 2.12.0 no longer respects allowSnapshots parameter

[llengo-pl]

In 2.12.0 allowSnapshots parameter is overridden by hardcoding allowingSnapshots to false here. So the snapshot parent versions will be filtered out and a desired version is not found when one tries to update-parent to a snapshot version.

Since on master branch I see that UpdateParentMojo is changed quite substantially, and that allowingSnapshots param was reverted to null, I am created this issue just as a note so other users know that a problem exists.

[jarmoniuk]

Duplicate of #670. Can be closed.

@slachiewicz

[llengo-pl]

Apologies for the duplicate, I've looked through the issues before posting but it just didn't occur to me that the issue would be closed.