feat(contribute.ts): avoid duplicate invocation of compute step

[glamperd]

Adds guard to prevent race condition when conditions allow start of compute step

fix #268

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name: Pull Request
about: Open a PR for p0tion

Description

Adds guard against duplicate invocation of compute step

Fixes # (issue)

How Has This Been Tested?

Tested using local environment

Checklist:

• [x ] My code follows the style guidelines of this project
• [ x] I have performed a self-review of my own code
• [ x] I have commented my code, particularly in hard-to-understand areas
• [ x] I have made corresponding changes to the documentation
• [ x] My changes generate no new warnings
• [ x] Any dependent changes have been merged and published in downstream modules
• [ x] I reviewed the code of conduct and contributors' guide