Add "unstable" feature for wasip2 stdlib

Signed-off-by: Colin Murphy <[email protected]>

Author: cdmurph32

Cargo.toml

@@ -37,3 +37,4 @@ doc-comment = "0.3"
 
 [features]
 nightly = []
+unstable = []

src/lib.rs

@@ -1,6 +1,9 @@
 // wasip2 conditionally gates stdlib APIs.
 // https://github.com/rust-lang/rust/issues/130323
-#![cfg_attr(all(target_os = "wasi", target_env = "p2"), feature(wasip2))]
+#![cfg_attr(
+    all(target_os = "wasi", target_env = "p2", feature = "unstable"),
+    feature(wasip2)
+)]
 //! Temporary files and directories.
 //!
 //! - Use the [`tempfile()`] function for temporary files