Fix @everyone role deserialisation (#2716)

The `@everyone` role sometimes has a role position of -1, but not always!

src/builder/edit_role.rs

@@ -65,7 +65,7 @@ pub struct EditRole<'a> {
     mentionable: Option<bool>,
 
     #[serde(skip)]
-    position: Option<u16>,
+    position: Option<i16>,
     #[serde(skip)]
     audit_log_reason: Option<&'a str>,
 }
@@ -125,7 +125,7 @@ impl<'a> EditRole<'a> {
 
     /// Set the role's position in the role list. This correlates to the role's position in the
     /// user list.
-    pub fn position(mut self, position: u16) -> Self {
+    pub fn position(mut self, position: i16) -> Self {
         self.position = Some(position);
         self
     }

src/http/client.rs

@@ -2119,7 +2119,7 @@ impl Http {
         &self,
         guild_id: GuildId,
         role_id: RoleId,
-        position: u16,
+        position: i16,
         audit_log_reason: Option<&str>,
     ) -> Result<Vec<Role>> {
         let map = json!([{

src/model/guild/guild_id.rs

@@ -807,7 +807,7 @@ impl GuildId {
         self,
         http: impl AsRef<Http>,
         role_id: RoleId,
-        position: u16,
+        position: i16,
     ) -> Result<Vec<Role>> {
         http.as_ref().edit_role_position(self, role_id, position, None).await
     }

src/model/guild/member.rs

@@ -279,7 +279,7 @@ impl Member {
     /// more roles have the same highest position, then the role with the lowest ID is the highest.
     #[cfg(feature = "cache")]
     #[deprecated = "Use Guild::member_highest_role"]
-    pub fn highest_role_info(&self, cache: impl AsRef<Cache>) -> Option<(RoleId, u16)> {
+    pub fn highest_role_info(&self, cache: impl AsRef<Cache>) -> Option<(RoleId, i16)> {
         cache
             .as_ref()
             .guild(self.guild_id)

src/model/guild/mod.rs

@@ -1210,7 +1210,7 @@ impl Guild {
         &self,
         http: impl AsRef<Http>,
         role_id: RoleId,
-        position: u16,
+        position: i16,
     ) -> Result<Vec<Role>> {
         self.id.edit_role_position(http, role_id, position).await
     }

src/model/guild/partial_guild.rs

@@ -863,7 +863,7 @@ impl PartialGuild {
         &self,
         http: impl AsRef<Http>,
         role_id: RoleId,
-        position: u16,
+        position: i16,
     ) -> Result<Vec<Role>> {
         self.id.edit_role_position(http, role_id, position).await
     }

src/model/guild/role.rs

@@ -54,7 +54,7 @@ pub struct Role {
     /// position is higher.
     ///
     /// The `@everyone` role is usually either `-1` or `0`.
-    pub position: u16,
+    pub position: i16,
     /// The tags this role has. It can be used to determine if this role is a special role in this
     /// guild such as guild subscriber role, or if the role is linked to an [`Integration`] or a
     /// bot.