Auto merge of #18446 - bzbarsky:update-cssparser, r=SimonSapin

Update rust-cssparser to 0.20.2.

This reduces memory consumption of list-valued properties in the common case of one entry in the list.

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components/script/Cargo.toml

@@ -33,7 +33,7 @@ byteorder = "1.0"
 canvas_traits = {path = "../canvas_traits"}
 caseless = "0.1.0"
 cookie = "0.6"
-cssparser = "0.20"
+cssparser = "0.20.2"
 deny_public_fields = {path = "../deny_public_fields"}
 devtools_traits = {path = "../devtools_traits"}
 dom_struct = {path = "../dom_struct"}