Get install.sh working on CentOS

[mathemancer]

Problem

We've had some feedback that the installation script isn't working on CentOS.

Proposed solution

We should document the problem, or modify the script so it works on CentOS.

Additional context

I suspect the issue has to do with underlying firewall issues.

[mathemancer]

Marking as draft while we gather more info.

[mathemancer]

After going back-and-forth with the tester, this seems to have worked out on its own. It had to do with non-Mathesar configuration on the test machine.