gnu: Remove rust-derive-is-enum-variant-0.1.

* gnu/packages/crates-io.scm (rust-derive-is-enum-variant-0.1): Delete variable.

gnu/packages/crates-io.scm

@@ -17863,31 +17863,6 @@ pattern for arbitrary structs.")
 error-chain.")
     (license (list license:expat license:asl2.0))))
 
-(define-public rust-derive-is-enum-variant-0.1
-  (package
-    (name "rust-derive-is-enum-variant")
-    (version "0.1.1")
-    (source
-     (origin
-       (method url-fetch)
-       (uri (crate-uri "derive_is_enum_variant" version))
-       (file-name (string-append name "-" version ".tar.gz"))
-       (sha256
-        (base32 "15w18649m4h47pdpr04id0wv8br8bg606zvrafcrfijihicqib6h"))))
-    (build-system cargo-build-system)
-    (arguments
-     `(#:skip-build? #t
-       #:cargo-inputs
-       (("rust-heck" ,rust-heck-0.3)
-        ("rust-quote" ,rust-quote-0.3)
-        ("rust-syn" ,rust-syn-0.11))))
-    (home-page "https://github.com/fitzgen/derive_is_enum_variant")
-    (synopsis "Automatically derives predicates for enums")
-    (description
-     "This package automatically derives @samp{is_dog} and @samp{is_cat}
-methods for @samp{enum Pet @{ Dog, Cat @}}.")
-    (license (list license:asl2.0 license:expat))))
-
 (define-public rust-derive-more-0.99
   (package
     (name "rust-derive-more")