Update octokit/core 4.3.0 or higher to Resolve Corporate Proxy Access Issue

[kentnsw]

Summary
Accessing GitHub behind a corporate proxy is problematic with the current configuration, octokit v4.2.0.

Details
Refer to the related issue: octokit/octokit.js#2098 for more context.

This problem has been resolved since version 4.3.0, as noted here: semantic-release/github#87 (comment)

Current Configuration
The current version, octokit/core 4.2.0, was introduced through PR: #286. The PR does not specify why version 4.2.0 was chosen.

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Suggested Action

• Update octokit/core to version 4.3.0 or later to resolve the proxy issue.