Removing system requirements check leftovers

[VitjanZ]

Got the following error, cause this was checking for the presence of "system_requirements" which were previously removed.

Traceback (most recent call last):
  File "/home/vitjan/codeplain/plain2code.py", line 43, in <module>
    from system_config import system_config
  File "/home/vitjan/codeplain/system_config.py", line 42, in <module>
    system_config = SystemConfig()
                    ^^^^^^^^^^^^^^
  File "/home/vitjan/codeplain/system_config.py", line 20, in __init__
    self.requirements = self.config["system_requirements"]

[VitjanZ]

Tjaz verbally approved :)