chore(flagd): bump test-harness submodules to v3.8.0

[toddbaert]

PR #1752 inadvertently reverted both test-harness submodule pointers from v3.8.0 (7575a1dc) back to v3.7.0 (b507289c) when its stale main-merge was resolved. Restore both pointers to v3.8.0.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: c7d5cf2d-2fb4-4c12-8ce7-1d496f4f1e47

📥 Commits

Reviewing files that changed from the base of the PR and between 72c275c and c5b1d68.

📒 Files selected for processing (2)

• providers/flagd/test-harness
• tools/flagd-api-testkit/test-harness

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📝 Walkthrough

Walkthrough

Two Git submodule pointers (providers/flagd/test-harness and tools/flagd-api-testkit/test-harness) are updated to the same new commit hash (7575a1dc), previously at b507289c. No source code or logic is changed.

Changes

Test-harness submodule pointer update

Layer / File(s)	Summary
Advance both test-harness submodules providers/flagd/test-harness, tools/flagd-api-testkit/test-harness	Both submodule references are bumped from b507289c to 7575a1dc45f176e57e809748a712a555e9aa5d11.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: bumping the test-harness submodules to v3.8.0.
Description check	✅ Passed	The description accurately explains that stale merges reverted the pointers and this PR restores them to v3.8.0.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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