version query fails in rtwsfcnfmi_make_rtw_hook.m for MATLAB<R2020b

[farndt]

MATLAB versions before R2020b can not execute line 59 of rtwsfcnfmi_make_rtw_hook.m:

ver('MATLAB').Version
Error: Functions cannot be indexed using {} or . indexing.

Proposal:

version_struct = ver('MATLAB');
version = str2double(version_struct.Version);