fix typo

Author: RonnyPfannschmidt

testing/runtests_travis.py

@@ -9,6 +9,6 @@
 elif os.environ.get('SELFINSTALL'):
     call('python setup.py sdist', shell=True)
     call('easy_install dist/*', shell=True)
-    import pkg_ressources
-    dist = pkg_ressources.get_distribution('setuptools_scm')
+    import pkg_resources
+    dist = pkg_resources.get_distribution('setuptools_scm')
     assert dist.version != '0.0'