Change ownership of /opt/librenms and run composer as the librenms user

[skyblaster]

This patch performs the following and allows both test workflows to succeed:

• Change ownership of /opt/librenms to the librenms user
• Run composer as the librenms user

Hopefully you find this approach acceptable.
I have only tested with a very minimal instance running under rootless Podman.

[CLAassistant]

All committers have signed the CLA.

[skyblaster]

Hi @crazy-max
I hate to nag, but just curious if you've had the chance to look at this.