Update xmlbuilder to version 9.0.0 🚀

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Hello lovely humans,

xmlbuilder just published its new version 9.0.0.

State	Update 🚀
Dependency	xmlbuilder
New version	9.0.0
Type	dependency

This version is not covered by your current version range.

Without accepting this pull request your project will work just like it did before. There might be a bunch of new features, fixes and perf improvements that the maintainers worked on for you though.

I recommend you look into these changes and try to get onto the latest version of xmlbuilder.
Given that you have a decent test suite, a passing build is a strong indicator that you can take advantage of these changes by merging the proposed change into your project. Otherwise this branch is a great starting point for you to work on the update.

Do you have any ideas how I could improve these pull requests? Did I report anything you think isn’t right?
Are you unsure about how things are supposed to work?

There is a collection of frequently asked questions and while I’m just a bot, there is a group of people who are happy to teach me new things. Let them know.

Good luck with your project ✨

You rock!

🌴

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The new version differs by 12 commits .

• 03856cf 9.0.0
• 6407fb2 Added change log for v9.0.0
• 15d4f1a Remove node 4.0 and 5.0 from Travis CI
• 37731d9 Added tests for invalid chars
• b7da010 Removed text case options. This isn't the job of this library.
• 1f9b41a Follow XML 1.1 spec for valid chars instead of 1.0. Fixes #147
• 605aeb3 Added link to examples in the wiki. Fixes #143.
• 1da59e1 Merge pull request #145 from btsimonh/master
• 97192a0 Add tests for -ve options.offset and options.dontprettytextnodes
• 391b638 move setting og @newlinedefault and @prettydefault to constructor and otpions set to fix bug.
• 3f86e19 introduce a new option 'dontprettytextnodes' which when active, will suppress indent and LF for nodes which contain any text (and all child nodes).
• 2bc90b6 Allow negetive 'offset' < -1 to be used

See the full diff.

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