gnu: Add rust-wayland-scanner-0.21.

* gnu/packages/crates-io.scm (rust-wayland-scanner-0.21): New variable.

Signed-off-by: Efraim Flashner <efraim@flashner.co.il>

gnu/packages/crates-io.scm

@@ -19883,6 +19883,21 @@ you are working on custom wayland protocol extensions.
 Look at the crate wayland-client for usable bindings.")
     (license license:expat)))
 
+(define-public rust-wayland-scanner-0.21
+  (package
+    (inherit rust-wayland-scanner-0.23)
+    (name "rust-wayland-scanner")
+    (version "0.21.13")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (crate-uri "wayland-scanner" version))
+       (file-name
+        (string-append name "-" version ".tar.gz"))
+       (sha256
+        (base32
+         "17mp49v7w0p0x5ry628lj2llljnwkr9aj9g4bqqhfibid32jhf5z"))))))
+
 (define-public rust-wayland-server-0.23
   (package
     (name "rust-wayland-server")