Update to edition 2021

Cargo.toml

@@ -2,7 +2,7 @@
 name = "triagebot"
 version = "0.1.0"
 authors = ["Mark Rousskov <mark.simulacrum@gmail.com>"]
-edition = "2018"
+edition = "2021"
 
 [workspace]
 

parser/Cargo.toml

@@ -2,7 +2,7 @@
 name = "parser"
 version = "0.1.0"
 authors = ["Mark Rousskov <mark.simulacrum@gmail.com>"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 pulldown-cmark = "0.7.0"