Make plugin sanity check job voting again

The job hasn't fail with the reason it was marked non-voting for,
for a while now.

Closes-Bug: #2053026
Change-Id: I035925416c9420624ea5d55b6bc5c1b08fcacf25

zuul.d/project.yaml

@@ -44,9 +44,6 @@
         - tempest-multinode-full-py3:
             irrelevant-files: *tempest-irrelevant-files
         - tempest-tox-plugin-sanity-check:
-            # TODO(kopecmartin): non-voting until this is resolved:
-            # https://bugs.launchpad.net/tempest/+bug/2053026
-            voting: false
             irrelevant-files: &tempest-irrelevant-files-2
               - ^.*\.rst$
               - ^doc/.*$