fix: remove nightly requirement

src/calculator.rs

@@ -287,7 +287,7 @@ impl PyCalculator {
         //   or mode is not specified and map is osu!standard, as that will be the inferred mode
         if (self.mods.is_some() && self.mods.unwrap().rx())
             && ((self.mode.is_none() && map.inner.mode == GameMode::Osu)
-                || self.mode.contains(&GameMode::Osu))
+                || self.mode == Some(GameMode::Osu))
         {
             return self.performance_2019(map);
         }

src/lib.rs

@@ -1,5 +1,4 @@
 #![deny(clippy::all, nonstandard_style, rust_2018_idioms, unused, warnings)]
-#![feature(option_result_contains)]
 
 use self::{
     beatmap::PyBeatmap,