Function change_case::snake_case

pub fn snake_case(input: &str) -> String

Change to snake case

use change_case::snake_case;
assert_eq!(snake_case(""), "");
assert_eq!(snake_case("_id"), "id");
assert_eq!(snake_case("test"), "test");
assert_eq!(snake_case("test string"), "test_string");
assert_eq!(snake_case("Test String"), "test_string");
assert_eq!(snake_case("TestV2"), "test_v2");
assert_eq!(snake_case("version 1.2.10"), "version_1_2_10");
assert_eq!(snake_case("version 1.21.0"), "version_1_21_0");