Docker build takes a very long time to download dependencies

[JGreenlee]

docker compose -f docker-compose-dev.yml build is taking about 25 minutes. It gets stuck while downloading pip dependencies.

I have seen a bunch of

=> => # WARNING: Retrying (Retry(total=3, connect=None, read=None, redirect=None, status=None)) after connection
=> => #  broken by 'NewConnectionError('<pip._vendor.urllib3.connection.HTTPSConnection object at 0x7ff9c11989a0
=> => # >: Failed to establish a new connection: [Errno 113] No route to host')': /Docs/packages/dash/ 

and sometimes I have seen

=> => # SLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: self-signed certificate

Although it retries every package several times and takes forever, it does eventually seem to finish.

[JGreenlee]

I noticed this while working on #154 because I added dependencies, which requires re-building.
Upon testing that PR, @TeachMeTW also had to rebuild and noticed this issue.