♻️ Use of pydantic to manage config+env variables

FastAPI release has been updated allowing to use lifespan parameter
to prepare/shutdown sub components.

backend/config/config.sample.yaml

@@ -0,0 +1,14 @@
+app_name: carrramba-encore-rate
+
+http:
+  host: 0.0.0.0
+  port: 4443
+  cert: ./config/cert.pem
+
+db:
+  name: carrramba-encore-rate
+  host: 127.0.0.1
+  port: 5432
+  driver: postgresql+psycopg
+  user: cer
+  password: cer_password