--restart not working and faulty convergence with wrong restart files

[gasevic]

Describe the bug The --restart flag does not create any restart files when a calculation is not converging.

To Reproduce Steps to reproduce the behaviour:

1. Happens with struc.zip using xtb --restart struc.xyz using xtb 6.7.1. The failed convergence is an expected behavior.
2. Using xtb 6.3.0 restart files can be created that can be read in and lead to convergence with faulty Wiberg bond orders and wrong topology.