Improvements

• #4606: The stream reading timeout for rasa shell` is now configurable by using the environment variableRASA_SHELL_STREAM_READING_TIMEOUT_IN_SECONDS. This can help to fix problems when usingrasa shell`` with custom actions which run
  10 seconds or longer.

Bugfixes

• #5709: Reverted changes in 1.9.6 that led to model incompatibility. Upgrade to 1.9.7 to fix
  self.sequence_lengths_for(tf_batch_data[TEXT_SEQ_LENGTH][0]) IndexError: list index out of range
  error without needing to retrain earlier 1.9 models.

  Therefore, all 1.9 models except for 1.9.6 will be compatible; a model trained on 1.9.6 will need
  to be retrained on 1.9.7.

Miscellaneous internal changes

• #5631