ci: improve stalebot behavior/language

[Stebalien]

1. Remove the cutesy language, it's kind of insulting. Happy to revert this change if people feel strongly, but I really don't like it when companies do this kind of thing.
2. Extend the close delay for both PRs and issues to 72 hours. We don't really need a response within a day and requiring a response within a day is pretty demanding.

[github-actions]

Please update the PR title to match https://github.com/filecoin-project/lotus/blob/master/CONTRIBUTING.md#pr-title-conventions

[rjan90]

Please update the PR title to match https://github.com/filecoin-project/lotus/blob/master/CONTRIBUTING.md#pr-title-conventions

I updated the link here manually, as this linked to the wrong place. We are fixing the link in: #12371

PR title now matches the required format.

[github-actions]

Please update the PR title to match https://github.com/filecoin-project/lotus/blob/master/README.md#pr-title-conventions

PR title now matches the required format.

[rjan90]

I investigated why this PR failed the "PR Title Check" despite conforming to our conventions. The issue stems from a recent change in our workflow:

1. We switched from pull_request to pull_request_target to support checking PR titles from forks: fix(ci): support checking forks in PR-title check workflow #12367
2. This PR was submitted during the transition period.
3. As a result, two "PR Title Check" workflows are running:
   • The old Check PR Title (pull_request) workflow (now obsolete) is failing.
   • The new pull_request_target workflow is passing.

It's safe to ignore the failing check from the obsolete workflow.

Apologies for the confusion and noise in your PR.