[gnome-sdk-images] Rename webkitgtk4 -> webkitgtk3

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 534c362ebf4c1fb8e57a27bb94a14a6fc9299c7c
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Wed Nov 29 17:18:47 2017 -0600

    Rename webkitgtk4 -> webkitgtk3
    
    This will be way less confusing, and it's in line with all distros not
    named Fedora. webkitgtk4 can now be used for a GTK+ 4 build.

 org.gnome.Sdk.json.in |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index ab5a525..3f9c58e 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -758,7 +758,7 @@
             ]
         },
         {
-            "name": "webkitgtk4",
+            "name": "webkitgtk3",
             "cleanup-platform": [ "/libexec/webkit2gtk-4.0/MiniBrowser" ],
             "buildsystem": "cmake",
             "build-options" : {