Add chmod and relative path for COPY and ENTRYPOINT.

So far, actions failed with `python: can't open file 'main.py': [Errno 2] No such file or directory`

Dockerfile

@@ -2,8 +2,9 @@
 FROM python:3.8-slim-buster
 
 # Copies your code file from your action repository to the filesystem path `/` of the container
-COPY src/main.py /main.py
+COPY src/main.py ./main.py
 
 # Code file to execute when the docker container starts up (`entrypoint.sh`)
 RUN ls
-ENTRYPOINT ["python", "main.py"]
+RUN chmod +x main.py
+ENTRYPOINT ["python", "./main.py"]