Method readfp() of configparser class is removed in Python 3.12

[zdohnal]

Python 3.12 removed readfp() method, so all hplip tools/binaries give traceback, f.e.:

$ sudo /usr/lib/cups/backend/hpfax
/usr/share/hplip/base/g.py:305: SyntaxWarning: invalid escape sequence '\|'
  spinner = "\|/-\|/-"
/usr/share/hplip/base/g.py:355: SyntaxWarning: invalid escape sequence '\d'
  m = re.search('python(\d(\.\d){0,2})', ext_path) #get the python version where the .so file is found
/usr/share/hplip/base/logger.py:440: SyntaxWarning: invalid escape sequence '\<'
  elem_start = re.findall("(\<\W{0,1}\w+) ?", line)[0]
/usr/share/hplip/base/logger.py:441: SyntaxWarning: invalid escape sequence '\]'
  elem_finished = re.findall("([?|\]\]]*\>)", line)[0]
/usr/share/hplip/base/logger.py:443: SyntaxWarning: invalid escape sequence '\S'
  attrs = re.findall("(\S*?\=\".*?\")", line)
Traceback (most recent call last):
  File "/usr/lib/cups/backend/hpfax", line 86, in <module>
    from base.g import *
  File "/usr/share/hplip/base/g.py", line 240, in <module>
    sys_conf = SysConfig()
               ^^^^^^^^^^^
  File "/usr/share/hplip/base/g.py", line 185, in __init__
    ConfigBase.__init__(self, '/etc/hp/hplip.conf')
  File "/usr/share/hplip/base/g.py", line 90, in __init__
    self.read()
  File "/usr/share/hplip/base/g.py", line 131, in read
    self.conf.readfp(fp)
    ^^^^^^^^^^^^^^^^
AttributeError: 'ConfigParser' object has no attribute 'readfp'. Did you mean: 'read'?

I've switched the code to 'read_file(fp, self.filename)', which fixes it.

Patch attached.