Remove error::Error::description

The `description` method is deprecated since Rust 1.33.0, now we are on
MSRV of 1.41.1 we can remove it in favour of `Display`.

Author: heap-coder

src/miniscript/types/mod.rs

@@ -108,10 +108,6 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> error::Error for Error<Pk, Ctx> {
     fn cause(&self) -> Option<&dyn error::Error> {
         None
     }
-
-    fn description(&self) -> &str {
-        "description() is deprecated; use Display"
-    }
 }
 
 impl<Pk: MiniscriptKey, Ctx: ScriptContext> fmt::Display for Error<Pk, Ctx> {

src/policy/mod.rs

@@ -67,9 +67,6 @@ pub enum LiftError {
 }
 
 impl error::Error for LiftError {
-    fn description(&self) -> &str {
-        ""
-    }
     fn cause(&self) -> Option<&dyn error::Error> {
         None
     }