Remove useless code

crates/milli/src/update/upgrade/v1_16.rs

@@ -46,22 +46,3 @@ impl UpgradeIndex for Latest_V1_15_To_V1_16_0 {
         (1, 16, 0)
     }
 }
-
-#[allow(non_camel_case_types)]
-pub(super) struct Latest_V1_16_To_V1_17_0();
-
-impl UpgradeIndex for Latest_V1_16_To_V1_17_0 {
-    fn upgrade(
-        &self,
-        _wtxn: &mut RwTxn,
-        _index: &Index,
-        _original: (u32, u32, u32),
-        _progress: Progress,
-    ) -> Result<bool> {
-        Ok(false)
-    }
-
-    fn target_version(&self) -> (u32, u32, u32) {
-        (1, 17, 0)
-    }
-}