tools/setup-virtualenv.sh: bump up the version of tox to 2.9.1

2.8.1 brings an important fix, see
tox-dev/tox#515.

Signed-off-by: Kefu Chai <[email protected]>

Author: tchaikov

src/tools/setup-virtualenv.sh

@@ -84,7 +84,7 @@ if test -d wheelhouse ; then
     export NO_INDEX=--no-index
 fi
 
-pip $DISABLE_PIP_VERSION_CHECK --log $DIR/log.txt install $NO_INDEX --find-links=file://$(pwd)/wheelhouse 'tox >=1.9'
+pip $DISABLE_PIP_VERSION_CHECK --log $DIR/log.txt install $NO_INDEX --find-links=file://$(pwd)/wheelhouse 'tox >=2.9.1'
 if test -f requirements.txt ; then
     pip $DISABLE_PIP_VERSION_CHECK --log $DIR/log.txt install $NO_INDEX --find-links=file://$(pwd)/wheelhouse -r requirements.txt
 fi