chore: update c8 package and use monocart to collect the coverage correctly

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 90.74%. Comparing base (dbc760d) to head (63de555).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2560 +/- ## ========================================== - Coverage 95.00% 90.74% -4.27% ========================================== Files 66 66 Lines 4546 2646 -1900 Branches 661 526 -135 ========================================== - Hits 4319 2401 -1918 + Misses 182 77 -105 - Partials 45 168 +123 ``` | [Flag](https://app.codecov.io/gh/vaadin/hilla/pull/2560/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vaadin) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/vaadin/hilla/pull/2560/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vaadin) | `90.74% <ø> (-4.27%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=vaadin#carryforward-flags-in-the-pull-request-comment) to find out more.

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vaadin / hilla

chore: update c8 package and use monocart to collect the coverage correctly #2560

Codecov Report

Quality Gate passed