feat(ci): improve dependency graph (#84)

Reviewed-on: #84
Co-authored-by: Joao P Dubas <joao.dubas+gitea@gmail.com>
Co-committed-by: Joao P Dubas <joao.dubas+gitea@gmail.com>

.drone.yml

@@ -11,11 +11,13 @@ steps:
   - name: database healthcheck
     image: &postgres 'postgres:16.3-alpine'
     environment:
-      PGUSER: postgres
+      PGUSER: &db_user postgres
-      PGPASSWORD: postgres
+      PGPASSWORD: &db_pass postgres
-      PGHOST: db
+      PGHOST: &db_host db
     commands:
       - while ! pg_isready; do sleep 1; done
+    depends_on:
+      - 'db'
 
   - name: restore cache
     image: &drone_cache 'meltwater/drone-cache:v1.4.0'
@@ -49,14 +51,16 @@ steps:
       - mix do local.rebar --force, local.hex --force, deps.get, deps.compile
       - mix compile --force --all-warnings --warnings-as-errors
     volumes: *volumes
+    depends_on:
+      - 'restore cache'
 
   - name: test
     image: *elixir
     environment:
       MIX_ENV: test
-      POSTGRES_HOST: &db_host db
+      POSTGRES_HOST: *db_host
-      POSTGRES_USER: &db_user postgres
+      POSTGRES_USER: *db_user
-      POSTGRES_PASS: &db_pass postgres
+      POSTGRES_PASS: *db_pass
     commands:
       - apt-get update
       - apt-get install -y git make