Dockerfile - updated transformers version to 4.31.0

[a-zurcher]

Building the docker image using docker build . -t tts didn't work for me, it gave the following error :
error: tokenizers 0.15.1 is installed but tokenizers!=0.11.3,<0.14,>=0.11.1 is required by {'transformers'}

I checked requirements.txt and found that the required transformers version was 4.31.0 instead of 4.29.2. After updating that line in the Dockerfile, the docker build command worked.

[rsxdalv]

this should be mergeable. 4.31.0 is indeed the long running and tested version

[manmay-nakhashi]

Sounds good, merging