Warning on `beta` as dep and `rc` as latest

[omid]

There is a warning for the dependency below:

[dependencies]
clap = "3.0.0-beta.5"

When I run cargo outdated, it gives:

warning: cannot compare clap crate version found in toml ^3.0.0-beta.5 with crates.io latest 3.0.0-rc.8

Based on semver, it seems they are comparable.