xtb version 6.4.1

Bugfix and maintenance release, some new features sneaked in here as well (COSMO solvation model).

Thanks to Marcel Stahn (@MtoLStoN), Sebastian Spicher (@sespic), Christoph Plett (@cplett), Cyrille Lavigne (@clavigne) and Miguel Steiner (@steinmig) for contributing to this version.

• Bugfix: topological charges in GFN-FF are now calculated correctly (#462) 🪲
• Bugfix: projector matrix is now setup correctly in xtb-thermo subprogram (#441) 🪲
• Bugfix: more stable parallelisation of numerical differentation (#465) 🪲
• Bugfix: caching logic in Turbomole runner is fixed (#448) 🪲
• Bugfix: transcription errors in (unused) STO-NG tables fixed (#464) 🪲
• consistent solvent names for hexane (#436)
• threadsafe caching for GFN-FF neighbourlists and charges (#467)
• hessian projection of fixed atoms works now for L-ANCopt (#433)
• COSMO solvation model for xTB (#274, #450)
• Turbomole runner will use aoforce instead of numerical differentiation (#470)
• reduced memory footprint for integral evaluation (#473)
• cleanup test names for meson build (#460)
• spurious warning for --parallel option fixed (#457)
• turn unconverged SCF into actual error (#485)
• fix keyword documentation for ESP grid file (#489)