We test in proto area not in site-packages.

--- pipdeptree-2.17.0/tox.ini.orig
+++ pipdeptree-2.17.0/tox.ini
@@ -25,7 +25,7 @@
     _COVERAGE_SRC = {envsitepackagesdir}/sphinx_argparse_cli
 commands =
     python -m pytest {tty:--color=yes} {posargs: \
-      --cov {envsitepackagesdir}{/}pipdeptree --cov {toxinidir}{/}tests \
+      --cov pipdeptree --cov {toxinidir}{/}tests \
       --cov-config=pyproject.toml --no-cov-on-fail --cov-report term-missing:skip-covered --cov-context=test \
       --cov-report html:{envtmpdir}{/}htmlcov --cov-report xml:{toxworkdir}{/}coverage.{envname}.xml \
       --junitxml {toxworkdir}{/}junit.{envname}.xml \