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 @@ (define-public jbig2dec
     (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 @@ (define-public jbig2dec
 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