In our simple use cases they both should generate the same code, see
[0] for notable differences. While we cannot drop proc-macro due to
that switch, all of our dependencies that use pinning already use
pin-project-lite, so this allows us to drop a whole crate in general
while not loosing anything.
[0]: https://github.com/taiki-e/pin-project-lite#pin-project-vs-pin-project-lite
Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>