fix: fix compilation warnings when running only with default features (#160)

* fix: fix compilation warnings when running only with default features
Co-authored-by: Luis Moreno <morenol@users.noreply.github.com>

src/algorithm/neighbour/fastpair.rs

@@ -1,5 +1,3 @@
-#![allow(non_snake_case)]
-use itertools::Itertools;
 ///
 /// # FastPair: Data-structure for the dynamic closest-pair problem.
 ///
@@ -177,6 +175,7 @@ impl<'a, T: RealNumber, M: Matrix<T>> FastPair<'a, T, M> {
     ///
     #[cfg(feature = "fp_bench")]
     pub fn closest_pair_brute(&self) -> PairwiseDistance<T> {
+        use itertools::Itertools;
         let m = self.samples.shape().0;
 
         let mut closest_pair = PairwiseDistance {