Make addressing deprecations acceptable in a patch release

[greg0ire]

Prompted by https://github.com/doctrine/orm/pull/10736

Addressing a deprecation is not a bugfix, it does not make the software more stable. Deprecations are annoying though, and unless we switch to using the ~ operator instead of the ^ operator for our dependencies, we might get new ones out of the blue. I propose to explicitly allow PRs that address deprecations in patch releases, so that users do not have to wait until the next minor to have fewer deprecations.