fix(cmake): remove zlib inclusion

`zlib.cmake` module was removed in #2174
but `userspace/sysdig/CMakeLists.txt` still includes it

Related to Homebrew/homebrew-core#258081

Signed-off-by: botantony <antonsm21@gmail.com>

Author: botantony

userspace/sysdig/CMakeLists.txt

@@ -20,7 +20,6 @@ if(NOT WIN32)
 	include(ncurses)
 endif() # NOT WIN32
 
-include(zlib)
 include(luajit)
 
 include_directories("${PROJECT_BINARY_DIR}/userspace/sinspui")