rust: migrate to [email protected]

Closes #62694.

Signed-off-by: FX Coudert <[email protected]>

Formula/rust.rb

@@ -2,6 +2,7 @@ class Rust < Formula
   desc "Safe, concurrent, practical language"
   homepage "https://www.rust-lang.org/"
   license any_of: ["Apache-2.0", "MIT"]
+  revision 1
 
   stable do
     url "https://static.rust-lang.org/dist/rustc-1.46.0-src.tar.gz"
@@ -30,7 +31,7 @@ class Rust < Formula
   end
 
   depends_on "cmake" => :build
-  depends_on "python@3.8" => :build
+  depends_on "python@3.9" => :build
   depends_on "libssh2"
   depends_on "[email protected]"
   depends_on "pkg-config"
@@ -53,7 +54,7 @@ class Rust < Formula
   end
 
   def install
-    ENV.prepend_path "PATH", Formula["python@3.8"].opt_libexec/"bin"
+    ENV.prepend_path "PATH", Formula["python@3.9"].opt_libexec/"bin"
 
     # Fix build failure for compiler_builtins "error: invalid deployment target
     # for -stdlib=libc++ (requires OS X 10.7 or later)"