* Update u6.py, fix mistake in docstrings

Change the numbers in the docstrings of setDOState() getDIState() and getDIOState().
The docstrings state that arguments ioNum = 20, 21, 22 access the so called MIO digital I/O. The class BitStateRead will take the argument mod 20, s.t. the user intending to read MIO1 reads FIO1 etc. The hardware documentation states that MIO 0-2 are shared with CIO 0-2.

* Update u6.py, Remove the lines defining the MIO numbers

Remove the lines defining the MIO numbers. This is more consistent with the low level function documentation:
https://labjack.com/pages/support?doc=/software-driver/low-level-ud-users-guide/bitstatewrite-iotype11/

ctypes.c_byte is specified to be equivalent to a signed char (-128 to 127) but we were passing unsigned char values (0-255) so we should be using ctypes.c_ubyte.

SafeConfigParser was removed in Python 3.12+, so changing to the replacement ConfigParser.

Needs testing and documentation updates.

* Needed for rawSHT1X