fix(sqlite): remove depends_on db, for #46

[stasadev]

The Issue

• For can't install when no db installed (I'm using SQLite) #46

ddev config --omit-containers=db
ddev dotenv set .ddev/.env.adminer --adminer-default-driver=sqlite --adminer-default-db=/mnt/ddev_app/test.sqlite
ddev add-on get ddev/ddev-adminer
ddev restart
...
Failed to restart demo-project: service "adminer" depends on undefined service "db": invalid compose project

How This PR Solves The Issue

We don't need depends_on, I would like to add it conditionally, but Docker Compose doesn't support that.

Manual Testing Instructions

ddev config --omit-containers=db
ddev dotenv set .ddev/.env.adminer --adminer-default-driver=sqlite --adminer-default-db=/mnt/ddev_app/test.sqlite
ddev add-on get ddev/ddev-adminer --pr 57
ddev restart
ddev exec sqlite3 test.sqlite "CREATE TABLE items(id INTEGER PRIMARY KEY, name TEXT); INSERT INTO items(name) VALUES ('alpha'), ('beta');"
ddev adminer

Automated Testing Overview

Release/Deployment Notes