Updating Lemmy binary

[Nutomic]

The Lemmy binary is directly committed into the git repo for now because thats the easiest option. To ensure it has a compatible glibc version it should be built in Docker by running this in Lemmy repo:

sudo docker build . -f docker/Dockerfile -t lemmy-plugins --build-arg RUST_RELEASE_MODE=release

Then use these instructions to extract the binary.

Later we could write a script to extract the binary from the latest release.