Allow heapsize 0.4

Author: Eijebong

Cargo.toml

@@ -21,7 +21,7 @@ encoding_rs = "0.5"
 
 [dependencies]
 cssparser-macros = {path = "./macros", version = "0.3"}
-heapsize = {version = "0.3", optional = true}
+heapsize = {version = ">= 0.3, < 0.5", optional = true}
 matches = "0.1"
 phf = "0.7"
 procedural-masquerade = {path = "./procedural-masquerade", version = "0.1"}