epiphany: 3.22.5 -> 3.22.6 for security issue

From https://bugzilla.gnome.org/show_bug.cgi?id=752738:

The page http://whatever.com has access to saved passwords of
https://whatever.com. This was a very bad idea: it makes it easy to
intercept passwords stored on secure websites, especially since we
don't require any user interaction to fill in the password.

No CVE has been assigned as of now.

cc #22549

pkgs/desktops/gnome-3/3.22/core/epiphany/src.nix

···
 # Autogenerated by maintainers/scripts/gnome.sh update
 
 fetchurl: {
-  name = "epiphany-3.22.5";
+  name = "epiphany-3.22.6";
 
   src = fetchurl {
     url = mirror://gnome/sources/epiphany/3.22/epiphany-3.22.5.tar.xz;
-    sha256 = "e9c307b3f53a77c16ca698fb62fbb8d9b16773702d8163d83699bd623afa6745";
+    sha256 = "0ib7z8x65gcr6vc6709df1rngcfrp3xn5ywqlrnc2xrsynrhghz9";
   };
 }