Switch to Python 3.7 for Flake8 tests.

.travis.yml

@@ -7,7 +7,7 @@ python:
   - 3.7
 matrix:
   include:
-    - python: 2.7
+    - python: 3.7
       name: "Flake8"
       install:  pip install -U flake8
       script: flake8 src setup.py

src/z3c/__init__.py

@@ -1,7 +1 @@
-# namespace package boilerplate
-try:
-    import pkg_resources
-    pkg_resources.declare_namespace(__name__)
-except ImportError, e:
-    from pkgutil import extend_path
-    __path__ = extend_path(__path__, __name__)
+__import__('pkg_resources').declare_namespace(__name__)

tox.ini

@@ -22,7 +22,7 @@ deps =
     coverage-python-version
 
 [testenv:flake8]
-basepython = python2.7
+basepython = python3.7
 skip_install = true
 deps = flake8
 commands = flake8 src setup.py