gnu: jbig2dec: Update source and home page URIs.

The old downloads.ghostscript.com returns a bogus 200 response, while
the new home page lists a different source.

Reported by Gábor Boskovits <boskovits@gmail.com>.

* gnu/packages/image.scm (jbig2dec)[source, home-page]: Update URIs.

gnu/packages/image.scm

@@ -487,8 +487,9 @@ arithmetic ops.")
     (source
       (origin
         (method url-fetch)
-        (uri (string-append "http://downloads.ghostscript.com/public/" name "/"
-                            name "-" version ".tar.gz"))
+        (uri
+         (string-append "https://github.com/ArtifexSoftware/ghostpdl-downloads/"
+                        "releases/download/gs922/" name "-" version ".tar.gz"))
         (sha256
           (base32 "0k01hp0q4275fj4rbr1gy64svfraw5w7wvwl08yjhvsnpb1rid11"))
         (patches (search-patches "jbig2dec-ignore-testtest.patch"))))
@@ -504,7 +505,7 @@ This is a decoder only implementation, and currently is in the alpha
 stage, meaning it doesn't completely work yet.  However, it is
 maintaining parity with available encoders, so it is useful for real
 work.")
-    (home-page "http://www.ghostscript.com/jbig2dec.html")
+    (home-page "https://jbig2dec.com")
     (license license:gpl2+)))
 
 (define-public openjpeg