klippy-env is corrupted

[Jomik]

The klippy-env is created in the build image, in the /build directory. This results in a shebang like #!/build/klippy-env/bin/python at the top of all the binaries in the venv.
python works because it is symlinked to /usr/bin/python3, but pip and wheel both fail, because they try to access python in a place that does not exist.
We can either...

• sed the venv files after they have been made.
• Make the venv in /home/printer.
• Create a symlink in /build/klippy-env to /home/printer/klippy-env for the full loop 😄