Add `~const` bounds to rust grammar
diff --git a/Cargo.toml b/Cargo.toml
index 050459e..8e732c8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "ungrammar"
 description = "A DSL for describing concrete syntax trees"
-version = "1.14.8"
+version = "1.14.9"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/matklad/ungrammar"
 edition = "2018"
diff --git a/rust.ungram b/rust.ungram
index 0af0f25..d2ef552 100644
--- a/rust.ungram
+++ b/rust.ungram
@@ -573,7 +573,7 @@
 
 TypeBound =
   Lifetime
-| '?'? Type
+| ('?' | '~' 'const')? Type
 
 //************************//
 //        Patterns        //