Support for environment variables from files (Docker secrets)

[mbelangergit]

Description

For sensitive data like DB_PASS for the Postgres password, it would be great to be able to set environment variables files. We then could use Docker secrets to pass sensitive data to the application.

LinuxServer uses FILE__ and many of the other containers I use are using the suffix _FILE.

Desired Behavior

I would like to be able to define the DB user and password as this:

---
services:
  jellyseerr:
    image: ghcr.io/fallenbagel/jellyseerr:latest
    container_name: jellyseerr
    environment:
      - TZ=Asia/Tashkent
      - DB_TYPE=postgres
      - DB_USER_FILE=/run/secrets/mysecretpostgresuser
      - DB_PASS_FILE=/run/secrets/mysecretpostgrespassword
    ...

Additional Context

No response

Code of Conduct

• I agree to follow Seerr's Code of Conduct

[benja1006]

Taking a stab at this as my first commit. Hoping to have a progress pull request by the end of the weekend at the latest