Fix misspelling

[cameronsjo]

Here is a checklist you should tick through before submitting a pull request:

• Implementation is clean
• Code adheres to the existing coding standards; e.g. no curlies for one-line blocks, no redundant empty lines between methods or code blocks, spaces rather than tabs, etc.
• No ReSharper warnings
• There is proper unit test coverage
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• Xml documentation is added/updated for the addition/change
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• Link to the issue(s) you're fixing from your PR description. Use fixes #<the issue number>
• Readme is updated if you change an existing feature or add a new one
• Run either build.cmd or build.ps1 and ensure there are no test failures

Fixed misspelling of "Uper" to "Upper".

[hazzik]

Thanks