Create test for checking pulpcore version on plugin_template

[daviddavis]

Migrated from https://pulp.plan.io/issues/6299

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plugin_template should have a test to assert if setup.py.j2 has the latest pulpcore version as requirement https://github.com/pulp/plugin_template/blob/master/templates/bootstrap/setup.py.j2

[stale]

This issue has been marked 'stale' due to lack of recent activity. If there is no further activity, the issue will be closed in another 30 days. Thank you for your contribution!