Future isn't used anymore and can be removed as a dependency.

Author: delajozate

requirements.txt

@@ -1,6 +1,5 @@
 pycryptodome
 six
-future
 rsa
 ecdsa
 pyasn1

setup.py

@@ -39,7 +39,7 @@ def _cryptography_version():
     'pycryptodome': ['pycryptodome >=3.3.1, <4.0.0'] + pyasn1,
 }
 legacy_backend_requires = ['ecdsa <1.0', 'rsa'] + pyasn1
-install_requires = ['six <2.0', 'future <1.0']
+install_requires = ['six <2.0']
 
 # TODO: work this into the extras selection instead.
 install_requires += legacy_backend_requires
@@ -75,7 +75,6 @@ def _cryptography_version():
     setup_requires=['pytest-runner'],
     tests_require=[
         'six',
-        'future',
         'ecdsa',
         'pytest',
         'pytest-cov',