gnu: ruby-chunky-png: Update to 1.3.12.

* gnu/packages/ruby.scm (ruby-chunky-png): Update to 1.3.12.

gnu/packages/ruby.scm

@@ -1578,23 +1578,19 @@ to save time in the following ways:
     (license license:expat)))
 
 (define-public ruby-chunky-png
-  ;; There hasn't been a release since 2018/11/21 and there are test failures
-  ;; in that release, so use the latest commit.
-  (let ((revision "1")
-        (commit "143b9cd1412e49edd4f8b661c7cd9b22941f43c0"))
   (package
     (name "ruby-chunky-png")
-      (version (git-version "1.3.11" revision commit))
+    (version "1.3.12")
     (source
      (origin
        (method git-fetch)
        (uri (git-reference
              (url "https://github.com/wvanbergen/chunky_png.git")
-               (commit commit)))
+             (commit (string-append "v" version))))
        (file-name (git-file-name name version))
        (sha256
         (base32
-           "0wbcgfzymbpmmxsb04arc49a2icki6f2fc6d6sqgg8369mc67g9z"))))
+         "0hn8ap7iib47qkqdp0awmxgma11z0lmk1ca3lp7c97ykhv7ij1zs"))))
     (build-system ruby-build-system)
     (arguments
      `(#:test-target "spec"
@@ -1643,7 +1639,7 @@ integer math and a highly optimized saving routine.
 @item Interoperability with RMagick.
 @end itemize")
     (home-page "https://github.com/wvanbergen/chunky_png/wiki")
-      (license license:expat))))
+    (license license:expat)))
 
 (define-public ruby-text-hyphen
   (package