I have the same Problem.
Sorry, that I’m not so good at the command line tool.
Which commands I have to enter in the command line tool to fix this issu? How can I downgrade the packages?
if you use sudo aptitude install python (if this is the package that is actually stated in your error report) you should be presented with an information about the versions currently installed and if which one you want to downgrade. Just follow the details instructions.
I think I had used sudo aptitude install libpython-dev and aptitude resolved all unmet dependencies.