fix: set specific version for env_logger

Fixes a bug in our CI:

$ cargo build --features "${CARGO_FEATURES}" --all
error: package `rustix v0.38.1` cannot be built because it requires rustc 1.63 or newer, while the currently active rustc version is 1.61.0

The bug was due to a wildcard requirement that let the version of env_logger and consequently its deps to be arbitrary (and cargo prefers latest).

I left some other deps to be * in tokio-hyper example as these dependencies exist in other crates in this workspace and there they are defined with specific versions. env_logger was the only outlier.