[improve][ci] Disable stale bot

[asafm]

Motivation

Stale bot generates more noise than attributing any value to maintaining PR and issues.
There was a discussion on this hence it's time to make the first step.

Modifications

Disable the GitHub workflow which triggers the stale check

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

If the box was checked, please highlight the changes

• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

• doc
• doc-required
• doc-not-needed
• doc-complete

[asafm]

@tisonkun

[github-actions]

@asafm Please add the following content to your PR description and select a checkbox:

- [ ] `doc` <!-- Your PR contains doc changes -->
- [ ] `doc-required` <!-- Your PR changes impact docs and you will update later -->
- [ ] `doc-not-needed` <!-- Your PR changes do not impact docs -->
- [ ] `doc-complete` <!-- Docs have been already added -->

[tisonkun]

Perhaps just delete the whole file?

[asafm]

@tisonkun Deleted it

[tisonkun]

LGTM. Open for a while to accept comments.

I'll merge this patch in the next monday if no more objection.

[eolivelli]

+1