Fix make starter and add nightly build check

[joecorall]

Resolves #380 #357
Also tested make starter_dev on this PR and it successfully builds so think this also resolves #354

Before

make clean
make starter

Fails with

s6-envdir: fatal: unable to envdir /run/s6/container_environment: No such file or directory

After

make clean
make starter

Successfully builds

Tests

Also added a test on pushes to this repo to ensure make starter build production work. Added a nightly build to also perform the check and send failure notifications to #bots in Islandora Slack

[aOelschlager]

@joecorall Thank you for doing this! Edit note: I removed my original question here that was asking about an error with generate secrets on Windows because it was unrelated to the Windows test issue. I removed this for clarity in case anyone reads this in the future while trying to troubleshoot.

[ajstanley]

The code is all solid, and make starter works again,