Version_caused_issues_in_Linear_viscoelastic_example

[JacquesWeiWANG]

1. For latest FEniCSx version, we should replace .vector by .x.petsc_vec
2. In solver.py, line 25 fem.petsc.apply_lifting(self._b, [self._a], bcs=[self.bcs], x0=x0, scale = 1.0) delete scale = 1.0

[bleyerj]

Thanks, yes I should find time to pass everything to dolfinx v0.10.