change pet account label description

Previously, the description that appeared when clicking the pet account icon read: > This account has been marked as a pet by its owner. This is of course intended to match the automated account description (`This account has been marked as automated by its owner.`), which makes sense as 'automated' is a adjective, whereas 'pet' is a noun with pets usually having the property of 'having an owner', and can be slightly ambiguous as "it's owner" initially read to me as 'the owner of the pet' not the intended meaning of the 'the owner of the account', This patch changes the label to instead be > This account owner has marked this account as a pet. Which makes it more clear that the account owner did the action to the account. Technically it's still not fully correct as the account itsself isn't the pet in question but it's clearer, especially if the account owner wants it to make very clear that the 'pet' tag may not have been applied by the owner of the pet itsself, if the pet even has one.