fixed travis build

.travis.yml

@@ -23,8 +23,7 @@ before_install:
 
 install:
   - pip list
-  - pip install setuptools_scm  # the old pytest-cases and makefun that we use are not universal wheels, this is required by their setup.py
-  - pip install pytest_cases==1.10.1  # again just for python 2 !
+  - pip install setuptools_scm  # apparently python 2 requires this
   - python ci_tools/py_install.py pip ci_tools/requirements-pip.txt
   # this does not work anymore on python 2 so lets only do it when needed
   - if [ "${TRAVIS_PYTHON_VERSION}" = "3.5" ]; then pip install mkdocs-material mkdocs; fi;

ci_tools/requirements-pip.txt

@@ -6,8 +6,8 @@ stdlib_list
 # --- to run the tests
 pytest  #$PYTEST_VERSION
 pytest-logging  # ==2015.11.4
-pytest_cases==1.10.1  # we use that precise version otherwise there is a conflict with makefun 1.6.8
-makefun==1.6.8        # we use that precise version because it does not have the __version__ attribute.
+pytest_cases
+makefun
 
 # --- to generate the reports (see scripts in ci_tools, called by .travis)
 # pytest-cov==2.6.0  # after 2.6.1 it requires pytest 3.6