Scheduled python code can't find module when run in Docker

I’m trying to run a python script inside a Docker container every 2 minutes. To achieve this, I am using a cron job. When I run the Python script on the host machine, it executes perfectly, but inside the docker container I keep getting

ModuleNotFoundError: No module named 'requests'

The container builds perfectly fine, and the requirements are installed correctly according to the build log. My Dockerfile and cron job are as follows:

Dockerfile

    FROM python:latest 
    WORKDIR /root 
    COPY *.py . 
    COPY requirements.txt . 
    COPY cronjob.txt . 
    RUN pip install -r requirements.txt 
    RUN apt update 
    RUN apt install cron -y 
    RUN crontab -l | { cat; cat cronjob.txt; } | crontab -
    ENV PYTHONPATH "$PYTHONPATH:/usr/local/lib/python3.11/site-packages"
    CMD cron -f

cronjob.txt
*/2 * * * * python3 runSync.py > /proc/1/fd/1 2>/proc/1/fd/2

runSync.py

import requests


def run_sync(network, ips, port, endpoint):
    for ip in ips:
        out = ""
        try:
            url = "http://" + network.format(ip=ip, port=port) + endpoint
            print("Resolving " + url + "...")
            res = requests.get(url)
            if res.status_code != 200:
                raise ValueError("Unexpected status code: {code}".format(code=res.status_code))
            print(res)
            print("Success!")
        # TODO: Better error handling
        except requests.exceptions.Timeout:
            out = "Connection to server timed out."
            break
        except requests.exceptions.ConnectionError:
            out = "Unable to connect to server, please check internet connection."
            break
        except requests.exceptions.InvalidURL:
            out = "Malformed URL ", url, " please check and try again."
            break
        except KeyboardInterrupt:
            out = "Stopping..."
            break
        except ValueError as e:
            out = "Encountered error: "{error}"".format(error=e.args[0])
            break
    if out != "":
        return out
    else:
        return "Success"


if __name__ == '__main__':
    defaultNetwork = "192.168.33.{ip:n}:{port:n}"
    defaultPort = 8080
    defaultEndpoint = "/api/system/sync"
    defaultIPs = [29, 28, 12]
    out = run_sync(defaultNetwork, defaultIPs, defaultPort, defaultEndpoint)
    if out != "Success":
        print(out)
        exit(1)
    else:
        exit(0)

requirements.txt

requests==2.28.1

I’ve tried manually setting the PYTHONPATH (as seen in Dockerfile), as well as changing the application root to a couple of different options. I should be seeing the output of runSync.py in the docker logs, but instead I just get ModuleNotFoundError: No module named 'requests'.