Replace into_iter() with iter()

`into_iter()` has been deprecated for arrays in 1.41 and replaced with
`iter()`. See rust-lang/rust#66145 .

Signed-off-by: Joshua Sorenson <[email protected]>

Author: Shirtpantswallet

proptest/CHANGELOG.md

@@ -1,3 +1,10 @@
+## Unreleased
+
+### Deprecations
+
+- `into_iter()` has been deprecated for arrays in 1.41 and replaced with
+  `iter()`. See[Issue #66145](https://github.com/rust-lang/rust/issues/66145) .
+
 ## 0.9.4
 
 ### Bug Fixes

proptest/src/arbitrary/_std/io.rs

@@ -116,7 +116,7 @@ arbitrary!(ErrorKind, Union<Just<Self>>;
     , Other
     , UnexpectedEof
     // TODO: watch this type for variant-additions.
-    ].into_iter().cloned().map(Just))
+    ].iter().cloned().map(Just))
 );
 
 arbitrary!(