python: shut up "pip install" during "make check-minreqs"

python: shut up "pip install" during "make check-minreqs"

"make check-minreqs" runs pip without the --disable-pip-version-check
option, which causes the obnoxious "A new release of pip available"
message.

Recent versions of pip also complain that some of the dependencies in
our virtual environment rely on "setup.py install" instead of providing
a pyproject.toml file; apparently it is deprecated to install them
directly from pip instead of letting the "wheel" package take care
of them.  So, install "wheel" in the virtual environment.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Message-Id: <20230511035435.734312-2-jsnow@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>