ruby-nokogiri: update to 1.10.1.

Upstream changes (from CHANGELOG.md):

# 1.10.1 / 2019-01-13

### Features

* [MRI] During installation, handle Xcode 10's new library path.
  [#1801, #1851] (Thanks, @mlj and @deepj!)
* Avoid unnecessary creation of `Proc`s in many methods. [#1776]
  (Thanks, @chopraanmol1!)

### Bug fixes

* CSS selector `:has()` now correctly matches against any descendant.
  Previously this selector matched against only direct children).
  [#350] (Thanks, @Phrogz!)
* `NodeSet#attr` now returns `nil` if it's empty. Previously this
  raised a NoMethodError.
* [MRI] XPath errors are no longer suppressed during
  `XSLT::Stylesheet#transform`. Previously these errors were suppressed
  which led to silent failures and a subsequent segfault. [#1802]

(tsutsui)