fix: logger message to debug when plugins not found

[souvikg10]

Proposed changes:

• Fixes the logger.info when plugins not found to logger.debug

Status (please check what you already did):

• [x] made PR ready for code review
• [x] added some tests for the functionality
• [ ] updated the documentation in the rasaHQ/rasa
• [x] updated the changelog (please check changelog for instructions)
• [x] reformat files using black (please check Readme for instructions)

[xxm1668]

ModuleNotFoundError: No module named 'rasa_sdk_plugins'

[souvikg10]

@xxm1668 - what is the version you are trying to install? please install rasa-sdk==3.6.2

[xxm1668]

i find rasa==3.5.0 rasa-sdk==3.5.0,it works!!!

[souvikg10]

this change was only implemented in rasa-sdk==3.6.1 however there was a regression which was fixed in rasa-sdk==3.6.2