Remove python 3.5 support; add python 3.8 support

- Python 3.5 has reached end-of-life.
- Add support for Python 3.8
- Move dist to bionic (xenial is EOL in April)
- Upgrade pip in travis.yml's `before_install`. this should install a wheel
  for pyca/cryptography
- Install rust for pypy builds. It is a requirement for cryptography as no
  pypy wheels exist.

1 files changed, 2 insertions, 2 deletions

diff --git a/setup.py b/setup.py
index 0babb45..fed5814 100755
--- a/setup.py
+++ b/setup.py
@@ -34,7 +34,7 @@ setup(
     platforms='any',
     license='BSD',
     packages=find_packages(exclude=('docs', 'tests', 'tests.*')),
-    python_requires='>=3.5',
+    python_requires='>=3.6',
     extras_require={
         'rsa': rsa_require,
         'signedtoken': signedtoken_require,
@@ -51,9 +51,9 @@ setup(
         'Operating System :: POSIX :: Linux',
         'Programming Language :: Python',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
         'Programming Language :: Python :: 3 :: Only',
         'Programming Language :: Python :: Implementation',
         'Programming Language :: Python :: Implementation :: CPython',