Upgrade to ubuntu groovy (21.04)

Ubuntu 21.04 looks in terms of dependencies looks much more like the
current bmc builds today.  Namely, it includes systemd 246.

Tested:
Build sdbusplus with these changes pre-rebase.  Build succeeded.

Change-Id: Id52d6c5ee6a11a4af70d2bf789b306d069eb3971
Signed-off-by: Ed Tanous <edtanous@google.com>
1 file changed