gnu: rust-const-oid: Add 0.9.1.

* gnu/packages/crates-io.scm (rust-const-oid-0.9): New variable.
(rust-const-oid-0.6): Inherit from it.

gnu/packages/crates-io.scm

@@ -12313,8 +12313,32 @@ (define-public rust-const-fn-0.4
 const functions with conditional compilations.")
     (license (list license:asl2.0 license:expat))))
 
+(define-public rust-const-oid-0.9
+  (package
+    (name "rust-const-oid")
+    (version "0.9.1")
+    (source (origin
+              (method url-fetch)
+              (uri (crate-uri "const-oid" version))
+              (file-name (string-append name "-" version ".tar.gz"))
+              (sha256
+               (base32
+                "0fyxvwnl3x6bxhy08a3g4ryf8mky6wnhwd6ll4g6mjxgfnk1ihyf"))))
+    (build-system cargo-build-system)
+    (arguments
+     `(#:skip-build? #t))
+    (home-page "https://github.com/RustCrypto/formats/tree/master/const-oid")
+    (synopsis "Implementation of the ISO/IEC Object Identifier (OID)")
+    (description
+     "This package is a const-friendly implementation of the ISO/IEC Object
+Identifier (OID) standard as defined in ITU X.660, with support for BER/DER
+encoding/decoding as well as heapless no_std (i.e., embedded) support.")
+    ;; The user can choose either license.
+    (license (list license:asl2.0 license:expat))))
+
 (define-public rust-const-oid-0.6
   (package
+    (inherit rust-const-oid-0.9)
     (name "rust-const-oid")
     (version "0.6.2")
     (source
@@ -12324,15 +12348,7 @@ (define-public rust-const-oid-0.6
        (file-name (string-append name "-" version ".tar.gz"))
        (sha256
         (base32 "12vv7csqqjj0x1l5mf51lgqiw76k5c3mb1yzfhfcqysks2j2lvwx"))))
-    (build-system cargo-build-system)
+    (arguments `(#:skip-build? #t))))
-    (arguments `(#:skip-build? #t))
-    (home-page "https://github.com/RustCrypto/formats/tree/master/const-oid")
-    (synopsis "Implementation of the ISO/IEC Object Identifier (OID)")
-    (description
-     "This package is a const-friendly implementation of the ISO/IEC Object
-Identifier (OID) standard as defined in ITU X.660, with support for BER/DER
-encoding/decoding as well as heapless no_std (i.e., embedded) support.")
-    (license (list license:asl2.0 license:expat))))
 
 (define-public rust-const-random-0.1
   (package