Fixes #7383 by adding cppstd to QNX QCC in settings and #7426 by adding version 8.3 - #7384

Changelog: Bugfix: cppstd was missing in settings.yml for the qcc compiler and updates to 8.3.
Docs: Omit

I am not sure though if I also need to update the documents

Close #7383
Close #7426

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^{Note: By default this PR will skip the slower tests and will use a limited set of python versions. Check here how to increase the testing level by writing some tags in the current PR body text.}