pin older pip for tox under py37

this is suddenly failing due to a non-py37 syntax in
pip/_vendor/typing_extensions.py.  Not clear why the failure has just
started however as there is no new version of pip recently.

Change-Id: I783e2341424a1dad206a7ab668900475fd8d30c5

diff --git a/tox.ini b/tox.ini
index 26254801d723ce148992650649b6b2dbb53ef36e..d872bbc8fe8cc1782c0646cddcd2a2627136b82a 100644 (file)
--- a/tox.ini
+++ b/tox.ini
@@ -98,6 +98,9 @@ setenv=
     PYTHONNOUSERSITE=1
     PYTEST_EXCLUDES=-m "not memory_intensive and not mypy"
 
+    # ensure older pip is installed for EOL python versions
+    py37: VIRTUALENV_PIP=24.0
+
     PYTEST_COLOR={tty:--color=yes}
     MYPY_COLOR={tty:--color-output}