Home assitent add on - Docker does not find copied run.sh

I am currently trying to build my own Home Assitant Add on, but I am already desperate to get it to start. Home Assitant plugins are just Docker containers.
So I have created 5 files according to the official documentation here a Dockerfile, a config.json, a run.sh (which simply starts the fints_mqtt that is in the directory).
The requirements.txt is self-explanatory.
My Dockerfile looks like this :

FROM python:3.9-slim

RUN apt-get update && \
    apt-get install -y --no-install-recommends \
    libxml2-dev \
    libxslt-dev \
    gcc \
    && rm -rf /var/lib/apt/lists/*

COPY requirements.txt /

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

# Copy data for add-on
COPY run.sh /
RUN chmod a+x /run.sh

CMD [ "/run.sh" ]

We’ll ignore the fact that I’m not copying my py file, but that doesn’t lead to my error in any case.

I can also install this add on without any problems and get the successful message in the log that all dependencies have been built and that the add on has been installed, as you can see here in the picture all the data mentioned in the Dockerfile is there.

But I always get this error

[FATAL tini (8)] exec /run.sh failed: No such file or directory

when starting the add on and I can’t explain why, because I just copy a simple file and execute it that should be no problem at all for docker and home assitant. I have also searched everywhere on the internet but I seem to be the only one who has this problem, does anyone have any tips on what my problem could be?

You can try doing CMD [“sh”, “run.sh”] instead of ./run.sh or adding #!/bin/bash to the top of the run.sh