fix entity persistence

[cebtenzzre]

A user on the Discord (andarotajo) reported that the state of entities in persistent namespaces was not being preserved across AppDaemon restarts.

This is my understanding of the history:

• June 23rd: 4.5.11 is known good
• Oct 3rd: commit 587789a ("match/case statements") caused the db to no longer save
• Oct 12th: 4.5.12 is released, including the above commit
• Oct 16th: commit 9ee8853 ("fixed existence check") causes the db to save properly again
• Oct 25th: commit 229d077 ("python 3.13 support") introduces the issue which causes the warning on startup about the entity not being found

I believe this PR should fix the most recent regression. I may add a proper test now that I understand which versions to compare with.