Docker- ModuleNotFoundError: No module named 'six'

I've got pip installation error for my docker container. If I explicitly install six inside the container using docker-compose run --rm app bash -c 'pip install six', it works but all my github actions still continue to fail. Is there a way to fix this without having to use --ignore-installed option? My Dockerfile is:

FROM lambci/lambda:build-python3.6

WORKDIR /usr/app

ARG requirements_file="requirements-dev.txt"

ADD . /usr/app
RUN pip install --upgrade pip

# Generate requirements files.
RUN cd svc && \
    pipenv lock --requirements --dev > requirements-dev.txt && \
    pipenv lock --requirements > requirements.txt

RUN python -m venv /ve
RUN source /ve/bin/activate \
    && pip install -r requirements.txt \
    && pip install -r ${requirements_file}

and I get the error:

Traceback (most recent call last):
  File "/ve/bin/pylint", line 5, in <module>
    from pylint import run_pylint
  File "/ve/lib/python3.6/site-packages/pylint/__init__.py", line 13, in <module>
    from pylint.checkers.similar import Run as SimilarRun
  File "/ve/lib/python3.6/site-packages/pylint/checkers/__init__.py", line 42, in <module>
    from pylint.checkers.base_checker import BaseChecker, BaseTokenChecker
  File "/ve/lib/python3.6/site-packages/pylint/checkers/base_checker.py", line 17, in <module>
    from pylint.config import OptionsProviderMixIn
  File "/ve/lib/python3.6/site-packages/pylint/config.py", line 49, in <module>
    from pylint import utils
  File "/ve/lib/python3.6/site-packages/pylint/utils/__init__.py", line 44, in <module>
    from pylint.utils.ast_walker import ASTWalker
  File "/ve/lib/python3.6/site-packages/pylint/utils/ast_walker.py", line 8, in <module>
    from astroid import nodes
  File "/ve/lib/python3.6/site-packages/astroid/__init__.py", line 166, in <module>
    __import__(module[:-3])
  File "/ve/lib/python3.6/site-packages/astroid/brain/brain_builtin_inference.py", line 15, in <module>
    import six
ModuleNotFoundError: No module named 'six'