Fix -py35 typo for dsvm-nodepool job

Otherwise, we don't flag python3 support properly.

Change-Id: I564467180feeb4e26a2d38a4782b72c6a40aecfd
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

jenkins/jobs/nodepool.yaml

@@ -76,7 +76,7 @@
       - devstack-checkout
       - shell: |
           #!/bin/bash -xe
-          if [ "{python}" == "py35" ]; then
+          if [ "{python}" == "-py35" ]; then
               export DEVSTACK_GATE_USE_PYTHON3=true
           fi
           export PYTHONUNBUFFERED=true