fix: Run tests only if the miniscript feature is..

..enabled, enable it by default

crates/chain/tests/common/mod.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "miniscript")]
+
 mod tx_template;
 #[allow(unused_imports)]
 pub use tx_template::*;

crates/chain/tests/common/tx_template.rs

@@ -1,3 +1,5 @@
+#![cfg(feature = "miniscript")]
+
 use rand::distributions::{Alphanumeric, DistString};
 use std::collections::HashMap;