Update apt package lists before install

[jdeanwallace]

Resolves https://github.com/tiny-pilot/tinypilot-pro/issues/1074

This PR runs apt-get update before installing our Debian packages to ensure that the APT package index is up-to-date.

I have tested this fix in TinyPilot Pro:

• https://github.com/tiny-pilot/tinypilot-pro/pull/1075