Bump PPA size for mythbuntu 0.25 ppa

The Mythbuntu 0.25 PPA is issuing daily builds for lucid through precise per the mythbuntu update policy (2 mythtv versions per ubuntu release and all mythtv versions at LTS until next LTS).

Recently with adding precise to the mix, it seems that the quota is going over every other night because the old packages aren't being purged rapidly enough.

We're currently at 3GB, can we please be bumped to 4GB so that this won't continue to happen? We will be dropping lucid for the 0.25 PPA after precise is marked as stable.