Poetry.lock python version error when building codabench

@bbearce It seems like there is a problem when trying to build deploy Codabench on the current develop branch:

 => CACHED [django 2/9] RUN apt-get update && apt-get install -y gcc build-essential && rm -rf /var/lib/apt/lists/*                                                                                             0.0s
 => CACHED [django 3/9] RUN curl -sSL https://install.python-poetry.org | python3 -                                                                                                                             0.0s
 => CACHED [django 4/9] RUN poetry config virtualenvs.create false                                                                                                                                              0.0s
 => CACHED [django 5/9] RUN poetry config virtualenvs.in-project false                                                                                                                                          0.0s
 => CACHED [django 6/9] COPY pyproject.toml ./                                                                                                                                                                  0.0s
 => ERROR [django 7/9] RUN poetry lock                                                                                                                                                                          0.7s
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 > [django 7/9] RUN poetry lock:                                                                                                                                                                                     
0.513 The currently activated Python version 3.9.20 is not supported by the project (3.9.19).                                                                                                                        
0.513 Trying to find and use a compatible version.                                                                                                                                                                   
0.584                                                                                                                                                                                                                
0.584 Poetry was unable to find a compatible version. If you have one, you can explicitly use it via the "env use" command.                                                                                          
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failed to solve: process "/bin/sh -c poetry lock" did not complete successfully: exit code: 1 

Looks like an easy fix.