Automatically open podman PR to update gvproxy version when there's a new release

[cfergeau]

When there's a gvisor-tap-vsock release, the podman Windows and macOS installers need to be updated to use the new version. This is currently done manually, it would be nice to automate this.
This was suggested here #461 (comment)
podman uses renovate, it's most likely possible to use https://docs.renovatebot.com/modules/manager/regex/ to do the update.

Example podman commits doing these updates after a release:
containers/podman@52caa0f
containers/podman@45e1ffb