There are plenty of other DLLs with their version set to Windows 7. Other DLLs have different Windows versions, including Windows XP, Vista, 7, 8, and 10.
Please explain why bumping the version of ntoskrnl is necessary in your commit message.
Also, I'm not sure if anything depends on the version, and if it does, the version bump may cause a regression due to unimplemented APIs.