Put a ceiling for urllib3 in tests (<2)

tox.ini

@@ -19,6 +19,7 @@ filterwarnings =
 [testenv]
 usedevelop=True
 commands =
+    pip install urllib3<2
     pip install pylxd
     python -m pytest --tb native -ra -v -s -n auto -k 'not integration' -m 'not serial' {posargs}
 passenv =
@@ -58,19 +59,22 @@ deps =
 [testenv:integration]
 envdir = {toxworkdir}/py3
 commands =
+    pip install urllib3<2
     pip install pylxd
     python -m pytest --tb native -ra -v -n auto -k 'integration' -m 'not serial' {posargs}
 
 [testenv:unit]
 envdir = {toxworkdir}/py3
 commands =
+    pip install urllib3<2
     pip install pylxd
     python -m pytest --tb native -ra -v -n auto {toxinidir}/tests/unit {posargs}
 
 [testenv:serial]
 # tests that can't be run in parallel
 envdir = {toxworkdir}/py3
 commands =
+    pip install urllib3<2
     pip install pylxd
     python -m pytest --tb native -ra -v -s {posargs:-m 'serial'}