Bump core stable versions to 10.3.7 and 11.0.6

Migrated issue

Reported by: fjgarlin

Related to !284 (merged)

Problem/Motivation

Core had two new releases:
- 10.3.7
- 11.0.6.

At least 10.3.7 is affected by #3485956: Recursion limit exceeded with Twig v3.14.1 when editing a node or a block, so we are not going to merge the version bump yet, but we can prepare the MR.