deps: upgrade to libuv 1.28.0

Notable changes:

• uv_gettimeofday() has been added.
• Streaming readdir() via the uv_fs_{open,read,close}dir() methods.
• A macOS copyfile() permissions bug has been fixed.
• A bug in uv_interface_addresses() on machines with multiple interfaces has been fixed.

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• tests and/or benchmarks are included
• commit message follows commit guidelines