gnu: Remove rust-chalk-derive-0.75.

* gnu/packages/crates-io.scm (rust-chalk-derive-0.75): Delete variable.

Change-Id: I20387b5a1ce24331979752640abb996cc68709f6

gnu/packages/crates-io.scm

@@ -11850,35 +11850,6 @@ chain, the first matching branch is the item that gets emitted.")
      "This package provides a macro to support `#[cfg()]` on visibility.")
     (license license:expat)))
 
-(define-public rust-chalk-derive-0.75
-  (package
-    (name "rust-chalk-derive")
-    (version "0.75.0")
-    (source
-     (origin
-       (method url-fetch)
-       (uri (crate-uri "chalk-derive" version))
-       (file-name
-        (string-append name "-" version ".tar.gz"))
-       (sha256
-        (base32
-         "0v1i5sb1w2skqg5sjy3gimdglsq0in6mc1zz36qyc99lkrgknknm"))))
-    (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)
-        ("rust-synstructure" ,rust-synstructure-0.12))))
-    (home-page "https://github.com/rust-lang/chalk")
-    (synopsis
-     "Helper crate for use by chalk crates for `derive` macros")
-    (description
-     "This package provides a helper crate for use by chalk crates for `derive`
-macros.")
-    (license (list license:asl2.0 license:expat))))
-
 (define-public rust-chan-0.1
   (package
     (name "rust-chan")