Fix warning in Cargo.toml.

Author: m-ou-se

macros/Cargo.toml

@@ -7,7 +7,7 @@ edition = "2018"
 repository = "https://github.com/fusion-engineering/inline-python"
 
 [lib]
-proc_macro = true
+proc-macro = true
 
 [dependencies]
 proc-macro2 = { version = "1.0", features = ["span-locations"] }