Add changes file for Qt 5.11.3

+ 43403038 Update bundled libtiff to version 4.0.10
+ 0c8d172c Update bundled libwebp to version 1.0.1
+ 7cfe47a8 TGA handler: check for out of range image size
+ 80017a1c Bundled libtiff: add a number of security-related upstream patches
+ 8455ab6c tiffhandler: improve stripsize
+ 2f61f401

 Bump version

Change-Id: If31999c0f727ce8b73e5ffb35e247d1106011bb9
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>