Failed build in gitlab CI/CD at requirements.txt - dockerfile

Question

The gitlab build fails with the following error:
WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/asgiref/
WARNING: Retrying (Retry(total=2, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/asgiref/
WARNING: Retrying (Retry(total=1, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/asgiref/
WARNING: Retrying (Retry(total=0, connect=None, read=None, redirect=None, status=None)) after connection broken by 'ReadTimeoutError("HTTPSConnectionPool(host='pypi.org', port=443): Read timed out. (read timeout=15)")': /simple/asgiref/
ERROR: Could not find a version that satisfies the requirement asgiref (from versions: none)
ERROR: No matching distribution found for asgiref
The command '/bin/sh -c pip install -r requirements.txt' returned a non-zero code: 1
Cleaning up file based variables
ERROR: Job failed: command terminated with exit code 1
My Dockerfile is the following:
FROM registry.ubitech.eu/public-group/ubitech-public-registry/python:3.8
COPY manage.py gunicorn-cfg.py requirements.txt ./
COPY core core
COPY routers routers
COPY data_utilities data_utilities
COPY datasets datasets
COPY monitoring monitoring
RUN pip install -r requirements.txt
COPY cron_3.0pl1-137_amd64.deb ./
RUN dpkg -i cron_3.0pl1-137_amd64.deb
RUN mkdir logs
RUN touch logs/onenet_dashboard.log
EXPOSE 5005
CMD ["gunicorn", "--config", "gunicorn-cfg.py", "core.wsgi"]
It is the first time that the build fails. Any idea of what is going wrong here?