gnu: Remove rust-ptree-0.3.

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

gnu/packages/crates-io.scm

@@ -70913,30 +70913,6 @@ pointers:
 configuration file and/or environment variables.")
     (license (list license:expat license:asl2.0))))
 
-(define-public rust-ptree-0.3
-  (package
-    (inherit rust-ptree-0.4)
-    (name "rust-ptree")
-    (version "0.3.1")
-    (source
-     (origin
-       (method url-fetch)
-       (uri (crate-uri "ptree" version))
-       (file-name (string-append name "-" version ".tar.gz"))
-       (sha256
-        (base32 "1bp6r88hcw0ygmdfdf1gwsj6krcah2qhwp3kw284wvni080l1zcm"))))
-    (arguments
-     `(#:skip-build? #t
-       #:cargo-inputs
-       (("rust-ansi-term" ,rust-ansi-term-0.12)
-        ("rust-atty" ,rust-atty-0.2)
-        ("rust-config" ,rust-config-0.10)
-        ("rust-directories" ,rust-directories-2)
-        ("rust-petgraph" ,rust-petgraph-0.5)
-        ("rust-serde" ,rust-serde-1)
-        ("rust-serde-value" ,rust-serde-value-0.6)
-        ("rust-tint" ,rust-tint-1))))))
-
 (define-public rust-windows-0.9
   (package
     (name "rust-windows")