add support for extra headers

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 69.23077% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 85.36%. Comparing base (c80bd32) to head (f7a419c).

Files	Patch %	Lines
internal/provider/provider.go	69.23%	3 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #495 +/- ## ========================================== - Coverage 85.41% 85.36% -0.06% ========================================== Files 80 80 Lines 7864 7877 +13 ========================================== + Hits 6717 6724 +7 - Misses 746 750 +4 - Partials 401 403 +2 ```

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