jose-jws: remove broken url feature

It was never actually declared properly in Cargo.toml and therefore
never worked (and therefore this is not actually a breaking change), but
also the code behind the feature does not otherwise compile, even if a
proper `url` optional dependency is added.

jose-jws/src/head.rs

@@ -27,11 +27,6 @@ pub struct Protected {
     #[serde(skip_serializing_if = "Option::is_none", default)]
     pub crit: Option<Vec<String>>,
 
-    /// RFC 8555 Section 6.4.1
-    #[cfg(feature = "url")]
-    #[serde(skip_serializing_if = "Option::is_none", default)]
-    pub url: Option<url::Url>,
-
     /// RFC 8555 Section 6.5.2
     #[serde(skip_serializing_if = "Option::is_none", default)]
     pub nonce: Option<Bytes>,
@@ -52,9 +47,7 @@ impl Default for Protected {
             nonce: None,
             b64: true,
             oth: Unprotected::default(),
-
-            #[cfg(feature = "url")]
-            url: None,
+            oth: Unprotected::default(),
         }
     }
 }
@@ -66,11 +59,6 @@ pub struct Unprotected {
     #[serde(skip_serializing_if = "Option::is_none", default)]
     pub alg: Option<Signing>,
 
-    /// RFC 7515 Section 4.1.2
-    #[cfg(feature = "url")]
-    #[serde(skip_serializing_if = "Option::is_none", default)]
-    pub jku: Option<url::Url>,
-
     /// RFC 7515 Section 4.1.3
     #[serde(skip_serializing_if = "Option::is_none", default)]
     pub jwk: Option<Jwk>,
@@ -79,11 +67,6 @@ pub struct Unprotected {
     #[serde(skip_serializing_if = "Option::is_none", default)]
     pub kid: Option<String>,
 
-    /// RFC 7515 Section 4.1.5
-    #[serde(skip_serializing_if = "Option::is_none", default)]
-    #[cfg(feature = "url")]
-    pub x5u: Option<url::Url>,
-
     /// RFC 7515 Section 4.1.6
     #[serde(skip_serializing_if = "Option::is_none", default)]
     pub x5c: Option<Vec<Bytes<Box<[u8]>, Base64>>>, // base64, not base64url