Updated tk-framework-qtwidgets to v2.12.8

Release notes: https://github.com/shotgunsoftware/tk-framework-qtwidgets/releases/tag/v2.12.8

Author: toolkitty

env/includes/common/frameworks.yml

@@ -19,7 +19,7 @@ frameworks:
       version: v1.2.11
   tk-framework-qtwidgets_v2.x.x:
     location:
-      version: v2.12.7
+      version: v2.12.8
       type: app_store
       name: tk-framework-qtwidgets
   tk-framework-shotgunutils_v4.x.x: