update ci to 5.12.3

Author: Skycoder42

.travis.yml

@@ -10,7 +10,7 @@ osx_image: xcode10.1
 env:
   global:
     - QDEP_CACHE_DIR=$HOME/.qdep-cache
-    - QT_VER=5.12.2
+    - QT_VER=5.12.3
     - DOCKER_IMAGE=base
     - MAKE_RUN_TESTS=true
     - TARGET_NAME=qtautoupdater

appveyor.yml

@@ -5,7 +5,7 @@ image:
 version: build-{build}
 
 environment:
-  QT_VER: 5.12.2
+  QT_VER: 5.12.3
   MAKE_RUN_TESTS: true
   TARGET_NAME: qtautoupdater