chore: drop Node 6

[curbengh]

What does it do?

Drop Node 6 as per #3508 . It has reached EOL since 2019-04-30.

How to test

git clone -b drop-node6 https://github.com/weyusi/hexo.git
cd hexo
npm install
npm test

Pull request tasks

• Passed the CI test.

[curbengh]

Some considerations:

• will there be v3.10.0?
  • it's still possible by creating a separate branch.
• might need the following in .eslintrc if someone wants to use ES2017/2018.

  "parserOptions": {
    "ecmaVersion": 2018
  }

[coveralls]

Coverage remained the same at 97.148% when pulling 75d23e2 on weyusi:drop-node6 into 7fba3c1 on hexojs:master.

[coveralls]

Coverage remained the same at 97.148% when pulling 5a61477 on weyusi:drop-node6 into 7fba3c1 on hexojs:master.

[yoshinorin]

will there be v3.10.0?

I think maybe no.

it's still possible by creating a separate branch.

I prefer to create a branch by new version. But, hexo team seems has never created new branch. (Sorry I'm not familiar with hexo team development flow)

IMO, we can merge this PR to master. Because, maybe we will not release a patch version.

[yoshinorin]

might need the following in .eslintrc in someone wants to use ES2017/2018.

I think maybe it's better to upgrade eslint-config-hexo.

@segayuu
How do you think?

[curbengh]

can someone restart the appveyor build with cleared cache?

[yoshinorin]

How about re-commit & force-push?
Or, disable cache settings once by appveyor.yml

[segayuu]

@yoshinorin eslint-config-hexo should be updated. It relies on eslint-config-node to properly manage the native API of node.js. Now that the LTS version of node.js has changed, it should be updated.

[curbengh]

I created a new PR for eslint-config-hexo (hexojs/eslint-config-hexo#16).

[curbengh]

How about re-commit & force-push?
Or, disable cache settings once by appveyor.yml

disable then re-enable cache works. Remember to squash them though.

[yoshinorin]

LGTM 👍