Add better error UX when spaces are found in required_conan_version

[AbrilRBS]

Changelog: (Fix): Display a better error when required_conan_version has spaces between the operator and the version.

This used to never allow the version check, even if the error was in the syntax, so now we just give a better error message

Closes #12692

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[CLAassistant]

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[memsharded]

Fantastic!