VERSION: update minimal version from 8 -> 12

[etroynov]

Hi,

The minimal node.js version which is supported by koa right now is 12, for this reason, I think that this package should also be updated, I have prepared it PR for you :)

Checklist

• [x] I have ensured my pull request is not behind the main or master branch of the original repository.
• [x] I have rebased all commits where necessary so that reviewing this pull request can be done without having to merge it first.
• [x] I have written a commit message that passes commitlint linting.
• [x] I have ensured that my code changes pass linting tests.
• [x] I have ensured that my code changes pass unit tests.
• [x] I have described my pull request and the reasons for code changes along with context if necessary.

[etroynov]

@dead-horse can you check this PR?

[etroynov]

@titanism what do you think about it?

[3imed-jaberi]

Fixed through this PR