More likely it because docker use cached parts of old builds. Here some steps.
1 Try manually full restart your docker
2 Manually delete last files from builds tab in docker program interface
3 Add this flag in dockerfile

RUN pip install --no-cache-dir -r requirements.txt

4 Add this flag in docker run command

docker build --no-cache -t

5 Starting build set version name you haven't use before

It's all need to make docker not use cached settings from old buildings.

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If it will not have any changes you can try the next command. !!! But pay attantion this command will delete all unusing images and volumes! Don't use if you got some important data! Then try repeat first five steps again.

docker system prune -a