style: fix ruff rule PLW1508

[PendaGTP]

SUMMARY

Fixes the lint rule PLW1508 (2 errors):

plugins/connection/proxmox_pct_remote.py:697:81: [PLW1508]
  Invalid type for environment variable default; expected `str` or `None`
  ⋮ │ 
696 │             chan.get_pty(
697 │                 term=os.getenv("TERM", "vt100"), width=int(os.getenv("COLUMNS", 0)), height=int(os.getenv("LINES", 0))
    │                                                                                 ↑
698 │             )
  ⋮ │ 

plugins/connection/proxmox_pct_remote.py:697:116: [PLW1508]
  Invalid type for environment variable default; expected `str` or `None`
  ⋮ │ 
696 │             chan.get_pty(
697 │                 term=os.getenv("TERM", "vt100"), width=int(os.getenv("COLUMNS", 0)), height=int(os.getenv("LINES", 0))
    │                                                                                                                    ↑
698 │             )
  ⋮ │