gnu: devhelp: Update to 3.20.0.

* gnu/packages/gnome.scm (devhelp): Update to 3.20.0.

gnu/packages/gnome.scm

@@ -2668,7 +2668,7 @@ which are easy to play with the aid of a mouse.")
 (define-public devhelp
   (package
     (name "devhelp")
-    (version "3.18.1")
+    (version "3.20.0")
     (source (origin
               (method url-fetch)
               (uri (string-append "mirror://gnome/sources/" name "/"
@@ -2676,7 +2676,7 @@ which are easy to play with the aid of a mouse.")
                                   name "-" version ".tar.xz"))
               (sha256
                (base32
-                "1vqsqpc51cir5qf801ibh6ljlpfw0qd513l9hjcnzp4ls8m1cfih"))))
+                "078zr92xs5ifp862v1vdmw1j9m6gr9zk5hjbk5065vxjwb17acx2"))))
     (build-system glib-or-gtk-build-system)
     (native-inputs
      `(("intltool" ,intltool)