fix browser test for jenkins worker

playbooks/roles/jenkins_worker/tasks/test_platform_worker.yml

@@ -23,7 +23,7 @@
   register: firefox_version
 - assert:
     that:
-      - "'42.0' in firefox_version.stdout"
+      - "'45.0.2' in firefox_version.stdout"
 
 # Verify the virtualenv tar is newly-built
 - name: Get info on virtualenv tar