* charm-helpers sync for classic charms
* build.lock file for reactive charms
* ensure tox.ini is from release-tools
* ensure requirements.txt files are from release-tools
* On reactive charms:
- ensure stable/21.04 branch for charms.openstack
- ensure stable/21.04 branch for charm-helpers
Change-Id: I95f8da0789b7f165677b031284acc4fadfdfeab4