Fix no_std builds by pulling in num-traits.

Cargo.toml

@@ -38,7 +38,7 @@ internals = []      # expose internal data structures
 unicode-xid-ident = ["unicode-xid"]  # allow Unicode Standard Annex #31 for identifiers.
 
 # compiling for no-std
-no_std = [ "no_closure", "hashbrown", "core-error", "libm", "ahash" ]
+no_std = [ "no_closure", "num-traits/libm", "hashbrown", "core-error", "libm", "ahash" ]
 
 [profile.release]
 lto = "fat"
@@ -51,6 +51,11 @@ version = "0.2.1"
 default_features = false
 optional = true
 
+[dependencies.num-traits]
+version = "0.2.11"
+default-features = false
+optional = true
+
 [dependencies.core-error]
 version = "0.0.0"
 default_features = false