Puppetboard

* Fix Puppetboard not starting on PE PuppetDB. ([711](https://github.com/voxpupuli/puppetboard/issues/711))

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* Make facts with integer values which are strings internally findable. ([706](https://github.com/voxpupuli/puppetboard/issues/706))

Thanks to [Stephen Ryan](https://github.com/ryaner) who contributed to this release!

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* Make the app work when installed from the git repo, f.e. using the [puppet-puppetboard module](https://github.com/voxpupuli/puppet-puppetboard). ([#704](https://github.com/voxpupuli/puppetboard/issues/704)).

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* Fix the Docker image - make the app start again. ([701](https://github.com/voxpupuli/puppetboard/issues/701)).
* Remove border-radius from the top menu to make it appear more clearly anchored to the page. ([699](https://github.com/voxpupuli/puppetboard/pull/699))

Thanks to [Marcel Deglau](https://github.com/promarcel) who contributed to this release!

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This is mostly a maintenance release.

The major version is bumped because of:
* dropped support for PuppetDBs < 5.2.0 (Puppet 4 has reached its end-of-life in October 2018),
* dropped support for Python 3.6 (end-of-life in December 2021).

There might be some performance improvements thanks to the upgrade of the core dependencies - Flask, Jinja2, Werkzeug etc.

Additional improvements:
* Set custom user-agent header that will make troubleshooting easier.

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* Stop modifying the query response for showing as JSON (fixes [695](https://github.com/voxpupuli/puppetboard/issues/695), PR [#696](https://github.com/voxpupuli/puppetboard/pull/696)).