We test in proto area not in site-packages.

--- filelock-3.13.3/tox.ini.orig
+++ filelock-3.13.3/tox.ini
@@ -27,7 +27,7 @@
     COVERAGE_FILE = {toxworkdir}{/}.coverage.{envname}
 commands =
     pytest {tty:--color=yes} {posargs: \
-      --junitxml {toxworkdir}{/}junit.{envname}.xml --cov {envsitepackagesdir}{/}filelock --cov {toxinidir}{/}tests \
+      --junitxml {toxworkdir}{/}junit.{envname}.xml --cov filelock --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 \
       tests