feat(slugbuilder):update stack to heroku-18-build

[duanhongyi]

Upgrade heroku-images to heroku-18-builder and update the latest release buildpacks

[Cryptophobia]

LGTM

[Cryptophobia]

Great work here @duanhongyi ! Did you test all of the example applications manually by deploying a custom image on minikube install or a test cluster?

[Cryptophobia]

Just one thing before we merge, can you change the commit message text to follow the commit-style 😁 : https://docs.teamhephy.com/contributing/submitting-a-pull-request/#commit-style

[duanhongyi]

Great work here @duanhongyi ! Did you test all of the example applications manually by deploying a custom image on minikube install or a test cluster?

Yes, it runs on minikube; I spent more than an hour using Python to write a set of test cases; Because I don't know much about golang, but I'm learning recently.

[Cryptophobia]

@duanhongyi :

The commit messages for both PRs is:
upgrade STACK to heroku-18
it should be something like this:
feat(slugbuilder):update stack to heroku-18-build (for slugbuilder)
and
feat(slugrunner):update stack to heroku-18
you can do it easily on each repo if you do this:
git reset --soft HEAD~1
then git add . && git commit

Sorry to ask about this but our release tool www.github.com/teamhephy/deisrel captures these commit messages and creates great changelogs that we use for new releases.

[Cryptophobia]

Thanks for changing the commit message to conform to our commit-style. Merged and it will be in the upcoming Hephy Workflow v2.20.0! 🥇