feat: add basic error handling

Add anyhow::Result<()> return signature to all scripts and main.

src/main.rs

@@ -36,7 +36,5 @@ fn main() -> Result<()> {
             cli::Postgres::Import { path } => scripts::postgres::import(&path),
             cli::Postgres::Dump { path } => scripts::postgres::dump(&path),
         },
-    };
-
-    Ok(())
+    }
 }