Change to Conventions breaking CMOR

[jonseddon]

Hi @wachsylon the change to the Conventions in commit 2eb9453 is breaking CMOR. It used to be:

"^CF-1.7 CMIP-6.[0-2]\( UGRID-1.0\)\{0,\}$"

but the commit changed it to:

"^CF-1\.7 CMIP-6\.0-2\{0,\}$"

is that needed for a specific tool in use at DKRZ? We're using CMOR 3.11.

If that's definitely required for another centre's tools then we'll cope with the change, but if it's not absolutely required then I might change it back.