gnu: Add rust-clap-conf.

* gnu/packages/crates-io.scm (rust-clap-conf-0.1): New variable.

gnu/packages/crates-io.scm

@@ -56909,6 +56909,35 @@ variant of this library is available separately as @code{im}.")
 (define-public rust-skim-0.7
   (deprecated-package "rust-skim-0.7" skim-0.7))
 
+(define-public rust-clap-conf-0.1
+  (package
+    (name "rust-clap-conf")
+    (version "0.1.5")
+    (source
+      (origin
+        (method url-fetch)
+        (uri (crate-uri "clap_conf" version))
+        (file-name
+          (string-append name "-" version ".tar.gz"))
+        (sha256
+          (base32
+            "1n29wr6ns660hi63mc30zvs7dhidaycw35am9spzknsal3nrs0sn"))))
+    (build-system cargo-build-system)
+    (arguments
+      `(#:cargo-inputs
+        (("rust-anyhow" ,rust-anyhow-1)
+         ("rust-clap" ,rust-clap-2)
+         ("rust-serde" ,rust-serde-1)
+         ("rust-thiserror" ,rust-thiserror-1)
+         ("rust-toml" ,rust-toml-0.5))))
+    (home-page
+      "https://github.com/storyfeet/clap_conf")
+    (synopsis
+      "A library to unify commandline arguments with config files and environment variables. And make it easier for users to tell your program how to behave across the three main input sources")
+    (description
+      "This package provides a library to unify commandline arguments with config files and environment variables.  And make it easier for users to tell your program how to behave across the three main input sources")
+    (license license:expat)))
+
 (define-public svd2rust
   (package
     (name "svd2rust")