Merge #90: Remove unused struct NewTrackerKey

728fe8a fix: [#78] remove unused struct NewTrackerKey (Jose Celano)

Pull request description:

  It was added because the tracker API was changed, but that change was reverted here:

  torrust/torrust-tracker#109

  and it is not used anymore.

ACKs for top commit:
  da2ce7:
    ACK 728fe8a

Tree-SHA512: 3bad8b9d0f38c0567e52d163c37fdc4dfde776d03666486416a833e290a29a7853e841853f7e5000ddeca9712ecebebecc200f86e97c647095dc6e36ceb13246

src/models/tracker_key.rs

@@ -7,12 +7,6 @@ pub struct TrackerKey {
     pub valid_until: i64,
 }
 
-#[derive(Debug, Serialize, Deserialize)]
-pub struct NewTrackerKey {
-    pub key: String,
-    pub valid_until: Duration,
-}
-
 #[derive(Debug, Serialize, Deserialize)]
 pub struct Duration {
     pub secs: i64,