Set a reasonable min version for serde_json

serde_json 1.0.25 brings in the json! macro that is used here
(https://github.com/serde-rs/json/releases/tag/v1.0.25)

Author: webmaster128

schemars/Cargo.toml

@@ -15,7 +15,7 @@ build = "build.rs"
 [dependencies]
 schemars_derive = { version = "=0.8.11", optional = true, path = "../schemars_derive" }
 serde = { version = "1.0", features = ["derive"] }
-serde_json = "1.0"
+serde_json = "1.0.25"
 dyn-clone = "1.0"
 
 chrono = { version = "0.4", default-features = false, optional = true }