[devhelp] build: bump WebKitGTK+ dependency to stable version

[Sébastien Wilmet <swilmet src gnome org>]

commit b764b5d181b38d7fe3d5755831c271d10d6e0a92
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Fri Mar 23 12:13:17 2018 +0100

    build: bump WebKitGTK+ dependency to stable version
    
    I prefer to specify stable versions.

 README      |    2 +-
 meson.build |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/README b/README
index 839d209..033afef 100644
--- a/README
+++ b/README
@@ -10,7 +10,7 @@ Dependencies
 
 - glib >= 2.56
 - gtk+ >= 3.22
-- webkit2gtk-4.0 >= 2.19.2
+- webkit2gtk-4.0 >= 2.20
 - gsettings-desktop-schemas
 
 Description
diff --git a/meson.build b/meson.build
index 8b7d37f..1834d3a 100644
--- a/meson.build
+++ b/meson.build
@@ -34,7 +34,7 @@ LIBDEVHELP_LT_VERSION='@0@.@1@.@2@'.format(lt_current, lt_revision, lt_age)
 libdevhelp_deps_array = [
         ['gio-2.0', '>= 2.56'],
         ['gtk+-3.0', '>= 3.22'],
-        ['webkit2gtk-4.0', '>= 2.19.2']
+        ['webkit2gtk-4.0', '>= 2.20']
 ]
 
 LIBDEVHELP_DEPS_STR = []