parser: fix dead_code warning in test parse_text fn

[sbdchd]

warning: function `parse_text` is never used
 --> crates/squawk_parser/tests/utils.rs:5:15
  |
5 | pub(crate) fn parse_text(text: &str) -> (String, bool) {
  |               ^^^^^^^^^^
  |
  = note: `#[warn(dead_code)]` on by default

warning: `squawk_parser` (test "utils") generated 1 warning
    Finished `test` profile [unoptimized] target(s) in 1.55s
     Running unittests src/main.rs (target/debug/deps/squawk-42ae9071a6dd104a)