use 2021 edition (#368)

jimexist · alamb · web-flow · commit d33bacf679df · 2021-12-08T15:44:20.000-05:00
Co-authored-by: Andrew Lamb &lt;andrew@nerdnetworks.org&gt;
diff --git a/Cargo.toml b/Cargo.toml
@@ -12,8 +12,7 @@ include = [
     "src/**/*.rs",
     "Cargo.toml",
 ]
-edition = "2018"
-resolver = "2"
+edition = "2021"
 
 [lib]
 name = "sqlparser"
