linfa-nn: bump kdtree to 0.7.0 (rust-ml#391)

0.6 has a known issue causing stack overflows on specific inputs, see mrhooray/kdtree-rs#42 (comment)

Co-authored-by: Alex Gessler <[email protected]>

Author: acgessler

algorithms/linfa-nn/Cargo.toml

@@ -31,7 +31,7 @@ noisy_float = "0.2.0"
 order-stat = "0.1.3"
 thiserror = "1.0"
 
-kdtree = "0.6.0"
+kdtree = "0.7.0"
 
 linfa = { version = "0.7.1", path = "../.." }