Update setup.py

Author: arvigj

setup.py

@@ -49,7 +49,8 @@ def build_extension(self, ext):
                       '-DPYTHON_EXECUTABLE=' + sys.executable,
                       '-DPYTHON_INCLUDE_DIR=' + python_include_directory,
                       '-DPOLYSOLVE_WITH_SPECTRA=OFF',
-                      '-DPOLYSOLVE_WITH_AMGCL=OFF']
+                      '-DPOLYSOLVE_WITH_AMGCL=OFF',
+                      '-DCMAKE_POLICY_VERSION_MINIMUM=3.5']
 
         cfg = 'Debug' if self.debug else 'Release'
         build_args = ['--config', cfg]