Remove unused imports from compact selection contracts

Signed-off-by: Daniel King <dan@spiraldb.com>

Author: danking

encodings/pco/src/range_selection_tests.rs

@@ -6,13 +6,11 @@ use std::sync::LazyLock;
 
 use pco::DEFAULT_MAX_PAGE_N;
 use rstest::rstest;
-use vortex_array::ArrayRef;
 use vortex_array::IntoArray;
 use vortex_array::VortexSessionExecute;
 use vortex_array::arrays::PiecewiseSequenceArray;
 use vortex_array::arrays::PrimitiveArray;
 use vortex_array::assert_arrays_eq;
-use vortex_array::session::ArraySessionExt;
 use vortex_array::validity::Validity;
 use vortex_error::VortexExpect;
 use vortex_error::VortexResult;