Bump unicode-normalization from 0.1.20 to 0.1.21 (#2160)

Bumps [unicode-normalization](https://github.com/unicode-rs/unicode-normalization) from 0.1.20 to 0.1.21.
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boa_engine/Cargo.toml

@@ -46,7 +46,7 @@ indexmap = "1.9.1"
 ryu-js = "0.2.2"
 chrono = "0.4.19"
 fast-float = "0.2.0"
-unicode-normalization = "0.1.20"
+unicode-normalization = "0.1.21"
 dyn-clone = "1.0.6"
 once_cell = "1.13.0"
 tap = "1.0.1"