fix(traverser): add generics to Traverser

[codecov[bot]]

Codecov Report

Patch and project coverage have no change.

Comparison is base (f4cf99f) 99.45% compared to head (ea9bcfe) 99.45%.

:exclamation: Current head ea9bcfe differs from pull request most recent head 111415b. Consider uploading reports for the commit 111415b to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #192 +/- ## ========================================= Coverage 99.45% 99.45% Complexity 129 129 ========================================= Files 10 10 Lines 367 367 ========================================= Hits 365 365 Misses 2 2 ``` | [Impacted Files](https://codecov.io/gh/SOF3/await-generator/pull/192?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonathan+Chan+Kwan+Yin) | Coverage Δ | | |---|---|---| | [...it-generator/src/SOFe/AwaitGenerator/Traverser.php](https://codecov.io/gh/SOF3/await-generator/pull/192?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonathan+Chan+Kwan+Yin#diff-YXdhaXQtZ2VuZXJhdG9yL3NyYy9TT0ZlL0F3YWl0R2VuZXJhdG9yL1RyYXZlcnNlci5waHA=) | `100.00% <ø> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonathan+Chan+Kwan+Yin). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Jonathan+Chan+Kwan+Yin)

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[SOF3]

@Endermanbugzjfc well those are out of scope of this PR