You can upgrade your version using command line,
Just open composer.json file from root, change
"version": "2.2.1", to "version": "2.2.2",
and
"magento/product-community-edition": "2.2.1", to "magento/product-community-edition": "2.2.2",
save composer.json file.
Run command from root of your system,
composer update
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