build: upgrade to 2024 edition

Author: paolobarbolini

.rustfmt.toml

@@ -10,7 +10,7 @@ version = "0.4.4"
 description = "Various helper types and macros for `diesel`"
 categories = ["database"]
 keywords = ["diesel", "postgresql", "enum", "macro", "json"]
-edition = "2021"
+edition = "2024"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/M4SS-Code/benzina"
 rust-version = "1.86"