CMake: move libdeflate and Lerc to Requires.private
This brings the CMake generated .pc file in line w/ the Autotools one: https://gitlab.com/libtiff/libtiff/-/blob/v4.6.0/configure.ac#L524
libdeflate.pc is shipped since v1.9 (Debian 11, CentOS 8, Ubuntu 22.04, ...)
Edited by Miloš Komarčević