Fix runtime error

[jcfr]

After:

1. building the extension based of COMP: Fix build system and update extension metadata #1
2. starting Slicer using the convenience launcher ./SlicerWithQuickModelAlign
3. selecting the QuickModelAlign module

.. the following errors are reported:

Select module	Error report

Python console:

Traceback (most recent call last):
  File "/path/to/Extension-Sources/QuickModelAlign-build/lib/Slicer-5.7/qt-scripted-modules/QuickModelAlign.py", line 95, in setup
    slicer.util.pip_install([wheelPath])
UnboundLocalError: local variable 'wheelPath' referenced before assignment

[jcfr]

Related:

• Add QuickModelAlign extension Slicer/ExtensionsIndex#1941