gnu: Add erlang-idna.

* gnu/packages/erlang-xyz.scm (erlang-idna): New variable.

Change-Id: I068e15dd505ceff0e66c97936445eaa3c980f803
Signed-off-by: Andrew Tropin <andrew@trop.in>

gnu/packages/erlang-xyz.scm

@@ -95,6 +95,23 @@ library for Erlang < 20.")
     (home-page "https://hex.pm/packages/unicode_util_compat")
     (license license:asl2.0)))
 
+(define-public erlang-idna
+  (package
+    (name "erlang-idna")
+    (version "6.1.1")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (hexpm-uri "idna" version))
+       (sha256
+        (base32 "1sjcjibl34sprpf1dgdmzfww24xlyy34lpj7mhcys4j4i6vnwdwj"))))
+    (build-system rebar-build-system)
+    (inputs (list erlang-unicode-util-compat))
+    (synopsis "Pure Erlang IDNA implementation")
+    (description "This package provides a pure Erlang IDNA implementation.")
+    (home-page "https://hex.pm/packages/idna")
+    (license license:expat)))
+
 (define-public erlang-base64url
   (package
     (name "erlang-base64url")