Rollup merge of #71068 - pyfisch:unicode-version-stable, r=SimonSapin

Stabilize UNICODE_VERSION (feature unicode_version)

Tracking issue: #49726

r? @sfackler

#71020 changed the definition of `UNICODE_VERSION` just yesterday from a struct to a tuple. Maybe you want to wait some more before stabilizing this constant, on the other hand this is a very small and simple addition.

CC @behnam @SimonSapin @Serentty

src/test/ui/char_unicode.rs

@@ -1,8 +1,6 @@
 // run-pass
 
-#![feature(unicode_version)]
-
-/// Tests access to the internal Unicode Version type and value.
+/// Tests access to the Unicode version constant.
 pub fn main() {
     check(std::char::UNICODE_VERSION);
 }