Fix deprecated usage of html5tokenizer in html-comments

[pwnxpl0it]

Hi, This PR fixes a compilation error related to the usage of a deprecated code from a yanked version of html5tokenizer (0.4.0) Versions

error: failed to compile `html-comments v0.1.0 (https://github.com/knassar702/hacks#a61a976a)`, intermediate artifacts can be found at `/tmp/cargo-installnpRfA6`

Caused by:
  failed to select a version for the requirement `html5tokenizer = "^0.4.0"`
  candidate versions found which didn't match: 0.5.2, 0.5.1, 0.5.0
  location searched: crates.io index
  required by package `html-comments v0.1.0 /home/user/.cargo/git/checkouts/hacks-5b2cd6b615994e27/a61a976/html-comments)`