gnu: Remove rust-async-recursion-0.3.

* gnu/packages/crates-io.scm (rust-async-recursion-0.3): Delete variable.

gnu/packages/crates-io.scm

@@ -4925,31 +4925,6 @@ implementing async state machines that can later be wrapped in dedicated
 futures.")
     (license (list license:expat license:asl2.0))))
 
-(define-public rust-async-recursion-0.3
-  (package
-    (name "rust-async-recursion")
-    (version "0.3.2")
-    (source
-     (origin
-       (method url-fetch)
-       (uri (crate-uri "async-recursion" version))
-       (file-name (string-append name "-" version ".tar.gz"))
-       (sha256
-        (base32 "18npixkwglnpvjgp89fpcyzf820ngx3a1hxp4hqbkw81p9b8dmyp"))))
-    (build-system cargo-build-system)
-    (arguments
-     `(#:skip-build? #t
-       #:cargo-inputs
-       (("rust-proc-macro2" ,rust-proc-macro2-1)
-        ("rust-quote" ,rust-quote-1)
-        ("rust-syn" ,rust-syn-1))))
-    (home-page "https://github.com/dcchut/async-recursion")
-    (synopsis "Recursion for async functions")
-    (description
-     "This package provides a procedural macro for recursive async
-functions.")
-    (license (list license:expat license:asl2.0))))
-
 (define-public rust-async-std-1
   (package
     (name "rust-async-std")