Increase tolerance of OrientedBoundingBoxVolume for test

\sitkLabelGeometryImageFilterTest.cxx(144): error: The difference
between 50909.54991064 and filter.GetOrientedBoundingBoxVolume( 1 ) is
0.001656065222050529, which exceeds 1e-007, where
50909.54991064 evaluates to 50909.549910640002,
filter.GetOrientedBoundingBoxVolume( 1 ) evaluates to
50909.551566705224, and
1e-007 evaluates to 9.9999999999999995e-008.

Change-Id: Ia7f4e91835aaf2f3ec36ecfe968fdb3644abb6e6
Merge topic 'SIMPLEITK-524_AddLabelGeometryImageFilter' into next

b199a9e9 Increase tolerance of OrientedBoundingBoxVolume for test