[READY] Update CI config

[bstaletic]

PR Prelude

Thank you for working on YCM! :)

Please complete these steps and check these boxes (by putting an x inside the brackets) before filing your PR:

• [x] I have read and understood YCM's CONTRIBUTING document.
• [x] I have read and understood YCM's CODE_OF_CONDUCT document.
• [x] I have included tests for the changes in my PR. If not, I have included a rationale for why I haven't.
• [x] I understand my PR may be closed if it becomes obvious I didn't actually perform all of these steps.

Why this change is necessary and useful

This is similar to ycm-core/ycmd#1746

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This change is