Drop include from prefix path

Author: Damir Porobic

.github/workflows/windows.yml

@@ -57,5 +57,5 @@ jobs:
         run: |
           mkdir build
           cd build
-          cmake .. -G"NMake Makefiles" -DCMAKE_PREFIX_PATH="$env:INSTALL_PREFIX/include"
+          cmake .. -G"NMake Makefiles" -DCMAKE_PREFIX_PATH="$env:INSTALL_PREFIX"
           nmake