I tried to install deepspeech library but it uninstalls numpy 1.17 version and installs numpy 1.14.4 (as deepspeech requires numpy version older than 1.14.5 version). This leads to error in rasa as rasa does not work on that old version of numpy.
unfortunately there is no command to prevent pip from downgrading dependencies. I would recommend to verify your numpy installation (1.17), clone the DeepSpeech repo, update the numpy version in requirements.txt and see if it works (most likely it will).
Thanks Julian.
I installed rasa once more after installing deepspeech and rasa once again updated numpy version but deepspeech is still working as it is not showing any error related to numpy.