Add polars to CI

Author: EricFecteau

Justfile

@@ -16,7 +16,8 @@ test +ARGS="":
     cargo test --features all {{ARGS}} -- --nocapture
 
 test-ci: 
-    cargo test --features src_postgres --features dst_arrow --test test_postgres 
+    cargo test --features src_postgres --features dst_arrow --test test_postgres
+    cargo test --features src_postgres --features src_dummy --features dst_polars --test test_polars
 
 test-feature-gate:
     cargo c --features src_postgres