Release activity 2.7.2

[phil-davis]

Reasons

• Needed to go with server core 10.13 because of the Symfony 4 to 5 upgrade owncloud/core#39630
• PR #1173 made code changes needed for Symfony 5
• #1181 (not yet merged)??

Note: the change in that PR also works fine with server core 10.12 and before, so there should be no need to bump the core min-version.

The app can be released any time before 10.13 - it should work fine with any of the recent oC10 core releases.

Needs full QA

• Testplan #1184

[jnweiger]

https://github.com/owncloud/activity/releases/download/v2.7.2-rc.1/activity-2.7.2-rc.1.tar.gz
https://github.com/owncloud/activity/releases/download/v2.7.2-rc.2/activity-2.7.2-rc.2.tar.gz

[jnweiger]

Release done together with 10.13.0