Postgres configuration should support `postgresql` scheme/protocol specifier

[BradStaton]

🐞 Describe the bug
In ntfy version 2.19.0 if NTFY_DATABASE_URL is set to a URL beginning with postgresql:// the application will fail to start with the message if database-url is set, it must start with postgres://. The postgresql:// option worked in version 2.18.0 and is the default format generated by CloudNativePG. The PostgreSQL documentation also uses postgresql:// when specifying connection URLs.

💻 Components impacted
ntfy server

💡 Screenshots and/or logs

if database-url is set, it must start with postgres://                                                                                                                                                
stream closed: EOF for ntfy/ntfy-5df644b984-474p8 (ntfy)   

🔮 Additional context
Ideally both postgresql:// and postgres:// should be supported.

[binwiederhier]

Apologies. I'll fix that in the next one

[BradStaton]

Thanks! I created a PR here.

[binwiederhier]

Thx