Add extra version of py-rsa (#15084)

var/spack/repos/builtin/packages/py-rsa/package.py

@@ -14,6 +14,7 @@ class PyRsa(PythonPackage):
 
     import_modules = ['rsa']
 
+    version('4.0',   sha256='1a836406405730121ae9823e19c6e806c62bbad73f890574fff50efa4122c487')
     version('3.4.2', sha256='25df4e10c263fb88b5ace923dd84bf9aa7f5019687b5e55382ffcdb8bede9db5')
 
     depends_on('py-setuptools', type=('build', 'run'))