Allow serde version in [0.7,0.9)

bigint/Cargo.toml

@@ -29,7 +29,7 @@ version = "0.3.19"
 
 [dependencies.serde]
 optional = true
-version = "0.7.0"
+version = ">= 0.7.0, < 0.9.0"
 
 [features]
 default = ["rand", "rustc-serialize"]

complex/Cargo.toml

@@ -22,7 +22,7 @@ version = "0.3.19"
 
 [dependencies.serde]
 optional = true
-version = "^0.7.0"
+version = ">= 0.7.0, < 0.9.0"
 
 [features]
 default = ["rustc-serialize"]

rational/Cargo.toml

@@ -30,7 +30,7 @@ version = "0.3.19"
 
 [dependencies.serde]
 optional = true
-version = "0.7.0"
+version = ">= 0.7.0, < 0.9.0"
 
 [features]
 default = ["bigint", "rustc-serialize"]