Update OptionsResolver.php

Deleting an extra space in the exception.
minor #10528 Update OptionsResolver.php (shadypierre)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10528).

Discussion
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Update OptionsResolver.php

Deleting an extra space in the exception.

Commits
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7507fbb Update OptionsResolver.php