Update remaining workflow files with consistent pytest version specifications

[Copilot]

This PR completes the pytest version specification updates started in #233 by updating the remaining GitHub Actions workflow files that still used the old version constraints.

Problem

While PR #233 successfully updated test-functions.yml and verify-module.yml to use modern pytest versions that resolve serialization issues, 4 other workflow files were left with the old version specifications:

• .github/workflows/run-examples.yml
• .github/workflows/test-functions-python313.yml
• .github/workflows/test-pip.yml
• .github/workflows/measure-coverage.yml

This inconsistency could lead to different pytest behaviors across workflows and potential serialization failures in parallel test execution.

Solution

Updated all remaining workflow files to use the same pytest version specifications established in #233:

• pytest>=7.4.0,<8.0.0 → pytest>=8.4.0
• pytest-xdist>=3.3.0,<4.0.0 → pytest-xdist>=3.8.0
• pytest-rerunfailures>=11.1,<12.0 → pytest-rerunfailures>=16.0

Also updated the comments to consistently reference "parallel execution" instead of "serialization issues" to match the style from #233.

Impact

• Consistency: All 6 GitHub Actions workflows now use identical pytest dependency versions
• Reliability: Eliminates potential serialization issues in parallel test execution across all workflows
• Performance: Ensures all workflows benefit from the improved pytest stability and parallel execution capabilities
• Maintainability: Prevents future confusion about which pytest versions should be used

Fixes #235.

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