Get the right version of tox in the wheelhouse

.circleci/populate-wheelhouse.sh

@@ -30,4 +30,5 @@ LANG="en_US.UTF-8" "${PIP}" \
     wheel \
     --wheel-dir "${WHEELHOUSE_PATH}" \
     "${PROJECT_ROOT}"[testenv] \
-    "${PROJECT_ROOT}"[test]
+    "${PROJECT_ROOT}"[test] \
+    "tox~=3.0"

.circleci/setup-virtualenv.sh

@@ -30,7 +30,7 @@ export PIP_NO_INDEX="1"
 
 # Get tox inside the bootstrap virtualenv since we use tox to manage the rest
 # of the environment.
-"${BOOTSTRAP_VENV}"/bin/pip install "tox~=3.0"
+"${BOOTSTRAP_VENV}"/bin/pip install tox
 
 # Get everything else installed in it, too.
 "${BOOTSTRAP_VENV}"/bin/tox \