chore(gatsby): Update broserslist dep

[grigiriy]

There is an error :
"Module build failed (from ./node_modules/postcss-loader/src/index.js):BrowserslistError: Browser queries must be an array or string. Got object."
and if I go deeper:
"Unknown browser query dead "

all other dependencies got 4+ version of browserslist package, which resolve this issue.

Got an issue when tried to migrate product based on "create react app" with "node-sass" package installed, to gatsby.

[pieh]

What are breaking changes between browserlist 3 and 4?

[pieh]

What are breaking changes between browserlist 3 and 4?

Answering my own question - https://github.com/browserslist/browserslist/blob/master/CHANGELOG.md#400-erinaceus-amurensis :

- Add node X and maintained node versions queries (by Pavel Vostrikov).
- Remove Node.js 4 support.
- Show warning if caniuse-lite is old (by Anton Tuzhik).
- Add comma support in config file.

So we should be good.

I'm still not clear for me how this fixes the error you described. But using latest browserslist seems good enough reason to bump.

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