Dependency hell: poem fails to build when hyper-util 0.1.1 is selected

[thornleywalker]

When built alone, or as the only dependency to a project, hyper-util 0.1.3 tends to be picked, which builds great. However, when hyper-util 0.1.1, the version specified in poem/Cargo.toml and poem-grpc.Cargo.toml, is selected (because of other dependencies, committed Cargo.lock, etc.) the poem crate can't build with the server feature, since the Builder::serve_connection_with_upgrades method used towards the end of poem/src/server.rs > serve_connection() has a different return type in 0.1.1 that doesn't implement graceful_shutdown().

Upgrading the dependency in poem/Cargo.toml (and probably poem-grpc/Cargo.toml) to 0.1.3 should fix it.