Pin the prettier version to specific version

[magsout]

I think it would be necessary to block the prettier version in package.json to avoid errors like here #1538 (comment)

The error is caused by a different version in the package.json. So every time we install prettier, or update all nodes module, we can cause an new error if there is a new update.

[miketaylr]

@magsout what do you mean by block?

https://github.com/webcompat/webcompat.com/blob/master/package.json#L43 has ^1.1.0 -- do you mean we pin to exactly a single version, so just 1.1.0?

[magsout]

@miketaylr yes exactly.

[miketaylr]

Cool, +1.

[zoepage]

Fixed in 182e77a