Remove Python 3.5 from test matrix

Also remove PyPy as I don't think a newer version is available on Travis
that isn't also really really slow.

.travis.yml

@@ -1,12 +1,8 @@
 language: python
-dist: xenial
-
 python:
-    - "3.5"
     - "3.6"
     - "3.7"
     - "3.8"
-    - pypy3.5-6.0
 
 matrix:
   include:

README.rst

@@ -94,7 +94,7 @@ Salmon has just had some major changes to modernise the code-base. The main
 APIs should be compatible with releases prior to 3.0.0, but there's no
 guarantee that older applications won't need changes.
 
-Python versions supported are: 3.5, 3.6, 3.7 and 3.8.
+Python versions supported are: 3.6, 3.7 and 3.8.
 
 See the CHANGELOG for more details on what's changed since Salmon version 2.
 

setup.py

@@ -40,7 +40,6 @@
         'License :: OSI Approved :: GNU General Public License v3 (GPLv3)',
         'Development Status :: 4 - Beta',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: 3.8',
@@ -50,7 +49,7 @@
         'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
         ],
-    'python_requires': '>=3.5',
+    'python_requires': '>=3.6',
     'entry_points': {
         'console_scripts':
             ['salmon = salmon.commands:main'],

tox.ini

@@ -3,7 +3,7 @@ envlist =
     docs
     lint
     isort
-    py{35,36,37,38}
+    py{36,37,38}
 
 [testenv]
 commands =