Consider using system CA store

[iaik-jheher]

PDF-Over currently bundles a JRE, and ends up using that bundled JRE's cacerts for SSL validation.

This tends to cause issues for enterprise users whose endpoint security wants to inspect TLS connections, and registers a device-specific inspection CA with the OS root store.

I'd want to look into switching from this Java-specific store to the OS root store, if feasible. No idea if it is, I haven't looked into it, just noting it down.