Add changes file for Qt 5.12.3

+ a075f064f0 Set OptimalParallelJobCount to at most 4
+ 22c66fa9f7 Use slerp for animating rotation channels
+ f72c8abf5f Fix light attenuation for ES 2
+ 4af8fcdc05 tests/auto/render/render.pro: Remove duplicate entry "scene2d"
+ 31aa763b0d Make slerping safer
+ a7e8df28c7 Fix member overloads
+ e9868e157b Don't reset texture units at every frame
+ eb33756771 Expand Scene3D documentation
+ 7a0d24164a Bump version
+ fa12f14b2b Scene3D: Call update on the item not the window
+ b79e4a8b2a Revert "Scene3D: Call update on the item not the window"
+ e84d8d2a81 Dont play animations that are disabled

Change-Id: I3badad7396927857bb4b5fedf46f1714dd992a27
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

dist/changes-5.12.3

@@ -0,0 +1,20 @@
+Qt 5.12.3 is a bug-fix release. It maintains both forward and backward
+compatibility (source and binary) with Qt 5.12.0 through 5.12.2.
+
+For more details, refer to the online documentation included in this
+distribution. The documentation is also available online:
+
+https://doc.qt.io/qt-5/index.html
+
+The Qt version 5.12 series is binary compatible with the 5.11.x series.
+Applications compiled for 5.11 will continue to run with 5.12.
+
+Some of the changes listed in this file include issue tracking numbers
+corresponding to tasks in the Qt Bug Tracker:
+
+https://bugreports.qt.io/
+
+Each of these identifiers can be entered in the bug tracker to obtain more
+information about a particular change.
+
+ - This release contains only minor code improvements.