Merge branch 'main' into precision-pcem

Release version 6.5.1 (grimme-lab#662)

Bump to version 6.5.0 (grimme-lab#618)

Fix gridfile keyword (grimme-lab#489)

Bump program version to 6.4.0 (grimme-lab#428)

Guard time estimate printout in hessian with omp critical (grimme-lab…

…#350)

Bump version number to 6.3.2 (grimme-lab#291)

Bump xtb version number to 6.3.1 (grimme-lab#254)

Add possibility to set numerical accuracy in API (grimme-lab#232)

- also give access to max iterations and electronic temperature
- add possibilities to access wavefunction
- remove initial newline from returned buffer

Patch user input to mopac to ensure gradient printout (grimme-lab#147)

- also warn user that input has been patched