Implement Scheduled CI Runs to Track Upstream AiiDA Changes

[harryswift01]

Summary

This PR extends the existing CI workflow by adding scheduled and manual triggers. The goal is to regularly validate the repository against upstream AiiDA changes, even when no local commits are made, and to allow maintainers to manually trigger CI runs when needed.

Changes

Add scheduled CI execution:

• Introduced a cron-based trigger to run the CI pipeline at a regular interval.
• Ensures automated detection of breaking changes or incompatibilities introduced by upstream AiiDA updates.
• Reuses the existing CI workflow to avoid duplication or increased maintenance overhead.

Add manual CI trigger (workflow_dispatch):

• Added a workflow_dispatch trigger to allow CI to be run manually from the GitHub UI.
• Enables ad‑hoc validation after upstream releases, debugging CI failures, or testing infrastructure changes without making code modifications.

Impact

• Improves early detection of upstream dependency changes affecting tests or documentation.
• Reduces long-term divergence from upstream AiiDA by surfacing issues proactively.
• Provides maintainers with greater control and flexibility over when CI is executed.
• Introduces minimal additional CI overhead while significantly improving robustness.

[coveralls]

Pull Request Test Coverage Report for Build 21243433598

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 81.949%

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Totals
Change from base Build 21242210947:	0.0%
Covered Lines:	1026
Relevant Lines:	1252

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💛 - Coveralls

[jimboid]

Looks good. This will stop these strange issues with aiida becoming incompatible with CI environments over time, by flagging it has happened closer to the time dependencies change and not when somebody sends a PR.