work around botocore pin

Author: laurenyu

tox.ini

@@ -57,7 +57,9 @@ passenv =
 
 # {posargs} can be passed in by additional arguments specified when invoking tox.
 # Can be used to specify which tests to run, e.g.: tox -- -s
+# TODO: Remove pip install python-dateutil==2.8.0 once botocore no longer requires a pinned version
 commands =
+    pip install python-dateutil==2.8.0
     coverage run --source sagemaker -m pytest {posargs}
     {env:IGNORE_COVERAGE:} coverage report --fail-under=90 --omit */tensorflow/tensorflow_serving/*
 extras = test
@@ -112,7 +114,9 @@ deps =
 # pip install requirements.txt is separate as RTD does it in separate steps
 # having the requirements.txt installed in deps above results in Double Requirement exception
 # https://github.com/pypa/pip/issues/988
+# TODO: Remove pip install python-dateutil==2.8.0 once botocore no longer requires a pinned version
 commands =
+    pip install python-dateutil==2.8.0
     pip install --exists-action=w -r requirements.txt
     sphinx-build -T -W -b html -d _build/doctrees-readthedocs -D language=en . _build/html