`run test` fails if I do not have pip

[pmbittner]

Apparently, the test script was changed to install missing python dependencies via pip from the requirements.txt. The nix setup does not work via pip, so I get errors.

Also, it might not be ideal to install things without asking the user. What about a warning instead?

[skrieter]

The script uses a virtual environment, so the system is not changed.

[pmbittner]

Oh I see. 🙊 It seems though that pip gets upgraded even if you do not want that to happen? 🤔

BibTags/scripts/test.sh

Lines 189 to 201 in 1bfd32c

	if [ -d "python/${python_env}" ]; then
	source python/${python_env}/bin/activate
	else
	if command -v pip3 &> /dev/null; then
	PIP=pip3
	else
	PIP=pip
	fi
	$PYTHON -m pip install --upgrade pip
	$PYTHON -m venv python/${python_env}
	source python/${python_env}/bin/activate
	$PIP install -r python/requirements.txt
	fi