Update README.md

[codecov[bot]]

Codecov Report

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

Project coverage is 60.27%. Comparing base (104efcd) to head (0d52c66).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #22 +/- ## ======================================= Coverage 60.27% 60.27% ======================================= Files 8 8 Lines 219 219 ======================================= Hits 132 132 Misses 58 58 Partials 29 29 ``` | [Flag](https://app.codecov.io/gh/kynmh69/go-ja-holidays/pull/22/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Hiroki+Kayanuma) | Coverage Δ | | |---|---|---| | [smart-tests](https://app.codecov.io/gh/kynmh69/go-ja-holidays/pull/22/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Hiroki+Kayanuma) | `60.27% <ø> (ø)` | | 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=Hiroki+Kayanuma#carryforward-flags-in-the-pull-request-comment) to find out more.

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