Bump version of tox in CI.

scripts/run-tests

@@ -7,7 +7,7 @@
 set -e
 
 python -m pip install --upgrade pip==19.1.1
-pip install tox==3.10.0
+pip install tox==3.14.0
 tox
 apk add --no-cache borgbackup
 tox -e end-to-end