workflow(lcov): update pull_requests.yml to exclude dir that do not need statistics

[davidshiz]

Summary about this PR

Issue Number: close #issue_number_you_created

Tests Check List

• [ ] Unit test
• [ ] Integration test
• [ ] Manual test (add detailed scripts or steps below)
• [ ] No code

Changelog

• [ ] New Feature
• [ ] Bug Fix
• [ ] Performance Improvement
• [x] Build/Testing/CI/CD
• [ ] Documentation
• [ ] Not for changelog (changelog entry is not required)

Documentation

• [ ] Affects user behaviors
• [ ] Contains syntax changes
• [ ] Contains variable changes
• [ ] Contains experimental features

[mergify[bot]]

Thanks for the contribution! I have applied any labels matching special text in your PR Changelog.

Please review the labels and make any necessary changes.

[codecov[bot]]

Codecov Report

Patch coverage has no change and project coverage change: -0.58 :warning:

Comparison is base (5606c87) 55.29% compared to head (551c2eb) 54.71%.

:exclamation: Current head 551c2eb differs from pull request most recent head 54716de. Consider uploading reports for the commit 54716de to get more accurate results

Additional details and impacted files

```diff @@ Coverage Diff @@ ## stonedb-5.7-dev #1904 +/- ## =================================================== - Coverage 55.29% 54.71% -0.58% =================================================== Files 2031 2030 -1 Lines 431536 431519 -17 =================================================== - Hits 238605 236101 -2504 - Misses 192931 195418 +2487 ``` [see 181 files with indirect coverage changes](https://app.codecov.io/gh/stoneatom/stonedb/pull/1904/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=stoneatom)

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