gnu: Remove icu4c-67.

* gnu/packages/icu4c.scm (icu4c-67): Remove variable.

gnu/packages/icu4c.scm

@@ -152,22 +152,6 @@ (define-public icu4c-70
                     (string-append "//" all))))))))
        (package-arguments icu4c)))))
 
-(define-public icu4c-67
-  (package
-    (inherit icu4c)
-    (version "67.1")
-    (source (origin
-              (method url-fetch)
-              (uri (string-append
-                    "https://github.com/unicode-org/icu/releases/download/release-"
-                    (string-map (lambda (x) (if (char=? x #\.) #\- x)) version)
-                    "/icu4c-"
-                    (string-map (lambda (x) (if (char=? x #\.) #\_ x)) version)
-                    "-src.tgz"))
-              (sha256
-               (base32
-                "1p6mhvxl0xr2n0g6xdps3mwzwlv6mjsz3xlpm793p9aiybb0ra4l"))))))
-
 (define-public icu4c-68
   (package
     (inherit icu4c)