eventually-postgres: library overhaul after latest changes (#87)

* feat(postgres): add migrations

* chore(postgres): add refinery dependency

* feat(postgres): overhaul the library

Author: ar3s3ru

eventually-postgres/Cargo.toml

@@ -17,6 +17,7 @@ eventually = { version = "0.4", path = "../eventually", features = ["serde"] }
 futures = "0.3"
 serde = "1.0"
 serde_json = "1.0"
-tokio = { version = "0.2", features = ["sync"] }
 tokio-postgres = { version = "0.5", features = ["with-serde_json-1"] }
 thiserror = "1.0"
+refinery = { version = "0.3.0", features = ["tokio-postgres"] }
+anyhow = "1.0.32"