slapos_web_deploy: support Ubuntu24.04

without the option --ignore-installed (even with
PIP_BREAK_SYSTEM_PACKAGES=1), pip3 upgrade on Ubuntu 24.04 would report:

Requirement already satisfied: pip in /usr/lib/python3/dist-packages (24.0)
Collecting pip
  Using cached pip-24.2-py3-none-any.whl.metadata (3.6 kB)
Using cached pip-24.2-py3-none-any.whl (1.8 MB)
Installing collected packages: pip
  Attempting uninstall: pip
    Found existing installation: pip 24.0
ERROR: Cannot uninstall pip 24.0, RECORD file not found. Hint: The package was installed by debian.