Workaround for cffi failing installation on cygwin

Author: abravalheri

noxfile.py

@@ -174,7 +174,7 @@ def chdir(path: Path):
         session.install("--no-build-isolation", str(examples / "html-py-ever"))
         session.run("pytest", str(examples / "html-py-ever"))
 
-        session.install("pytest", "cffi")
+        session.install("pytest", "cffi<1.16")
         session.install("--no-build-isolation", str(examples / "html-py-ever"))
         session.run("pytest", str(examples / "html-py-ever"))