Update koa-router to version 5.3.0 🚀

[greenkeeperio-bot]

Hello :wave:

:rocket::rocket::rocket:

koa-router just published its new version 5.3.0, which is not covered by your current version range.

If this pull request passes your tests you can publish your software with the latest version of koa-router – otherwise use this branch to work on adaptions and fixes.

Happy fixing and merging :palm_tree:

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The new version differs by 89 commits .

• e85b71e 5.3.0
• 919a53d Merge remote-tracking branch 'RobertHerhold/master' into 5.x
• 75b22ff Merge remote-tracking branch 'dizlexik/patch-1' into 5.x
• 814cdc3 Adding custom user-provided throw functions for "Not Implemented" and "Method Not Allowed"
• 33578d2 Sync with upstream and fix regexp issues
• e8e2b5e Allow specifying named routes and regexps
• b1abf24 5.2.3
• 2108cbe Do not register middleware more than once.
• a3958a8 5.2.2
• 10a4052 Merge remote-tracking branch 'Tankenstein/master'
• e486a93 Fix #182.
• 7207024 Add registering routes without params before routes with params
• d4d36fe Added test for registering without parameters ordering
• c8b4879 Improve app.context test for #181.
• 3da83f1 5.2.1

There are 89 commits in total. See the full diff.

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