Pin proptest version for now

Author: LLFourn

secp256kfun/Cargo.toml

@@ -36,7 +36,7 @@ serde_json = "1"
 rand = { version = "0.8" }
 lazy_static = "1.4"
 sha2 = "0.10"
-proptest = "1"
+proptest = "=1.6.0"
 criterion = "0.4"
 
 [target.'cfg(target_arch = "wasm32")'.dev-dependencies]