Fix: `DOWNLOAD_EXTRACT_TIMESTAMP` requires a bool
Before this, the download of the NatNetSDK and oscpkt failed with a message like this:
" is an existing non-empty directory".
This was caused as the input argument check was imporved in 3.27 and the
DOWNLOAD_EXTRACT_TIMESTAMP
was not set correctly.
This commit fixes this.
Also see this https://gitlab.kitware.com/cmake/cmake/-/issues/25107 for further information.