test(unit): exclude darwin from go build constraint

[wangxiaoxuan273]

What this PR does / why we need it: Removed darwin from go build constraint for pty-related operations. Tested on arm64 Mac and the tests pass.

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #1277

Please check the following list:

• [ ] Does the affected code have corresponding tests, e.g. unit test, E2E test?
• [ ] Does this change require a documentation update?
• [ ] Does this introduce breaking changes that would require an announcement or bumping the major version?
• [ ] Do all new files have an appropriate license header?

[codecov[bot]]

Codecov Report

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

Project coverage is 81.92%. Comparing base (d2cca28) to head (6cc1437).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #1289 +/- ## ========================================== - Coverage 81.97% 81.92% -0.06% ========================================== Files 83 83 Lines 3995 3995 ========================================== - Hits 3275 3273 -2 - Misses 497 499 +2 Partials 223 223 ```

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