Merge pull request matplotlib#29014 from tacaswell/fix/tox_ci

Author: timhoffm

tox.ini

@@ -12,6 +12,8 @@ setenv =
     MPLCONFIGDIR={envtmpdir}/.matplotlib
     PIP_USER = 0
     PIP_ISOLATED = 1
+    SETUPTOOLS_SCM_PRETEND_VERSION_FOR_MATPLOTLIB = 0.0.0
+
 usedevelop = True
 commands =
     pytest --pyargs matplotlib.tests  {posargs}