gempress: add missing package fields

lib/gempress/Cargo.toml

@@ -3,6 +3,8 @@ name = "gempress"
 version = "0.1.0"
 authors = ["Garrit Franke <garrit@slashdev.space>"]
 edition = "2018"
+description = "An Express.js inspired server framework for the gemini protocol"
+license = "MIT"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html