Rasa: 2.6.1 Release

Bugfixes

• #7908: Made SchemaError message available to validator so that the reason why reason schema validation fails during rasa data validate is displayed when response text value is null. Added warning message when deprecated MappingPolicy format is used in the domain.
• #8623: When there are multiple entities in a user message, they will get sorted when creating a representation of the current dialogue state.

Previously, the ordering was random, leading to inconsistent state representations. This would sometimes lead to memoization policies failing to recall a memorised action.