qcscine/readuct: Release 6.0.0

Changes:

• Add test for QM/MM transition state optimization
• Improve automatic mode selection by introducing a mode score considering a weighted sum of the contributions of the relevant atoms and the wavenumber of the mode.
• Add the option to export the selected mode of a transition state optimization.
• Enable thermochemistry calculations for single atoms
• The one-electron integrals may be written to file through a dedicated integral evaluation task
• Separated energy and gradient contributions in QM/MM can be requested with the keyword "require_partial_energies", and "require_partial_gradients" in the single-point task.