Added serde feature flags to tests

src/cluster/dbscan.rs

@@ -265,6 +265,7 @@ impl<T: RealNumber + Sum, D: Distance<Vec<T>, T>> DBSCAN<T, D> {
 mod tests {
     use super::*;
     use crate::linalg::naive::dense_matrix::DenseMatrix;
+    #[cfg(feature = "serde")]
     use crate::math::distance::euclidian::Euclidian;
 
     #[test]
@@ -299,6 +300,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "serde")]
     fn serde() {
         let x = DenseMatrix::from_2d_array(&[
             &[5.1, 3.5, 1.4, 0.2],

src/cluster/kmeans.rs

@@ -347,6 +347,7 @@ mod tests {
     }
 
     #[test]
+    #[cfg(feature = "serde")]
     fn serde() {
         let x = DenseMatrix::from_2d_array(&[
             &[5.1, 3.5, 1.4, 0.2],