Add extension_module in python example to skip linking against libpython.so and fix cargo build on unix systems (pola-rs#3358)

Co-authored-by: Maxime Jacques <[email protected]>

Author: Maxyme

examples/python_rust_compiled_function/Cargo.toml

@@ -11,4 +11,4 @@ crate-type = ["cdylib"]
 [dependencies]
 polars = { path = "../../polars" }
 polars-arrow = { path = "../../polars/polars-arrow" }
-pyo3 = "0.16"
+pyo3 = { version = "0.16.4", features = ["extension-module"] }