FindLibUV: Also check uv/version.h for version detection

Starting with libuv 1.21.0, libuv's headers were moved into a uv/ directory.
Make FindLibUV aware of the file's new location for configuration to work.
2 jobs for libuv-new-version-file-location
Status Job ID Name Coverage
  External
passed ghostflow-branch-check-master

passed ghostflow-commit-check