Set 'typing' package to be installed only on Python 2.7. This fixes the import issue raised

Python 3.7, on using the 'typing 3.6'.

Author: awais786

.travis.yml

@@ -12,6 +12,19 @@ python:
   - "pypy"
   - "pypy3.5-7.0" # Need 7.0+ due to a bug in earlier versions that broke our tests.
 
+matrix:
+  include:
+    - name: "Type checking"
+      python: "3.7"
+      env: TOXENV=typecheck
+    - name: "Lint"
+      python: "3.7"
+      env: TOXENV=lint
+
+  # Temporary bandaid for https://github.com/PyFilesystem/pyfilesystem2/issues/342
+  allow_failures:
+    - python: pypy
+    - python: pypy3.5-7.0
 
 before_install:
   - pip install -U tox tox-travis

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = {py27,py34,py35,py36,py37,py38}{,-scandir},pypy,typecheck,lint
+envlist = {py27,py34,py35,py36,py37}{,-scandir},pypy,typecheck,lint
 sitepackages = False
 skip_missing_interpreters=True