Fix build with CMake >= 3.28.0. FREETYPE_LIBRARY has not officially been
part of the user-facing interface of the FindFreetype module since CMake
2.6.0 [1] and has only been coincidentally defined up until this point.

[1] https://gitlab.kitware.com/cmake/cmake/-/commit/d18fb61c76c720ec5b1ac2cc4f30a5beaf071c33

--- src/CMakeLists.txt.orig	2023-12-26 21:03:32 UTC
+++ src/CMakeLists.txt
@@ -33,7 +33,7 @@ target_link_libraries(slvs_deps INTERFACE
     dxfrw
     ${ZLIB_LIBRARY}
     ${PNG_LIBRARY}
-    ${FREETYPE_LIBRARY}
+    ${FREETYPE_LIBRARIES}
     ${CAIRO_LIBRARIES}
     mimalloc-static)