Don't turn all warnings into errors with the default "strict" feature,
every new Rust release adds lints that break the build.

Bug: https://bugs.gentoo.org/961269
Upstream fixed the current warnings in:
https://github.com/influxdata/flux/pull/5560
https://github.com/influxdata/flux/pull/5568
https://github.com/influxdata/flux/pull/5585

--- a/libflux/flux/src/lib.rs
+++ b/libflux/flux/src/lib.rs
@@ -1,4 +1,3 @@
-#![cfg_attr(feature = "strict", deny(warnings, missing_docs))]
 
 //! This module provides the public facing API for Flux's Go runtime, including formatting,
 //! parsing, and standard library analysis.
--- a/libflux/flux-core/src/lib.rs
+++ b/libflux/flux-core/src/lib.rs
@@ -1,4 +1,3 @@
-#![cfg_attr(feature = "strict", deny(warnings, missing_docs))]
 #![allow(
     clippy::needless_update, //
     clippy::identity_op, // Warns on `1 * YEARS` which seems clearer than `YEARS`