bug about Implicit Small Strain Newmark method

[Jianming-Pu]

Describe the bug
When I used the solid implicit dynamic method to calculate problems, the calculation did not converge. So I checked the relevant code. Here, you can see that detJ is not reassigned after its initial value of 0, so none of the following calculations seem to make sense.

GEOS/src/coreComponents/physicsSolvers/solidMechanics/kernels/ImplicitSmallStrainNewmark_impl.hpp

Line 109 in 4696a65

real64 detJ=0;

I think there might be something wrong with the code.