No module named 'mymodule'

[KarlKeu00]

Hello everyone,
I have created a module exactly as instructed and only edited the signals.py file. I have pushed the whole module to a private GitHub repo and would now like to install it on my server.
I have written the following Dockerfile for this purpose:

FROM pretix/standalone:stable

USER root

# Copy ssh key for github
RUN mkdir -p -m 0700 /root/.ssh
COPY ./certs/id_rsa /root/.ssh/id_rsa
RUN chmod -R 0600 /root/.ssh/id_rsa

# Add key to ssh-agent
RUN eval $(ssh-agent -s) && \
    ssh-add /root/.ssh/id_rsa

# Add github.com to known_hosts and config
RUN ssh-keyscan github.com >> /root/.ssh/known_hosts
RUN echo "Host github.com\n\tHostname github.com\n\tIdentityFile /root/.ssh/id_rsa\n" >> /root/.ssh/config

# Install plugins
RUN pip3 install -U "git+ssh://git@github.com/MyProfile/Pretix-Plugins-MyModule.git"

# Build pretix
USER pretixuser
RUN cd /pretix/src && make production

pip installs the module correctly and it also appears in pip list. Why can't pretix find the module? I get the following error:

 => ERROR [9/9] RUN cd /pretix/src && make production                                                                                                0.8s
------
 > [9/9] RUN cd /pretix/src && make production:
0.139 ./manage.py compilemessages
0.729 Traceback (most recent call last):
0.729   File "/pretix/src/./manage.py", line 31, in <module>
0.729     execute_from_command_line(sys.argv)
0.729   File "/usr/local/lib/python3.11/site-packages/django/core/management/__init__.py", line 442, in execute_from_command_line
0.730     utility.execute()
0.730   File "/usr/local/lib/python3.11/site-packages/django/core/management/__init__.py", line 416, in execute
0.730     django.setup()
0.730   File "/usr/local/lib/python3.11/site-packages/django/__init__.py", line 24, in setup
0.730     apps.populate(settings.INSTALLED_APPS)
0.730   File "/usr/local/lib/python3.11/site-packages/django/apps/registry.py", line 91, in populate
0.731     app_config = AppConfig.create(entry)
0.731                  ^^^^^^^^^^^^^^^^^^^^^^^
0.731   File "/usr/local/lib/python3.11/site-packages/django/apps/config.py", line 193, in create
0.731     import_module(entry)
0.731   File "/usr/local/lib/python3.11/importlib/__init__.py", line 126, in import_module
0.732     return _bootstrap._gcd_import(name[level:], package, level)
0.732            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
0.732   File "<frozen importlib._bootstrap>", line 1204, in _gcd_import
0.732   File "<frozen importlib._bootstrap>", line 1176, in _find_and_load
0.732   File "<frozen importlib._bootstrap>", line 1140, in _find_and_load_unlocked
0.732 ModuleNotFoundError: No module named 'mymodule'
0.796 make: *** [Makefile:6: localecompile] Error 1
------
Dockerfile:24
--------------------
  22 |     # Build pretix
  23 |     USER pretixuser
  24 | >>> RUN cd /pretix/src && make production
  25 |     
--------------------
ERROR: failed to solve: process "/bin/sh -c cd /pretix/src && make production" did not complete successfully: exit code: 2