add conftest to avoid latex comaprisons

Author: mloubout

conftest.py

@@ -0,0 +1,8 @@
+import pytest
+
+
+@pytest.hookimpl(tryfirst=True)
+def pytest_collectstart(collector):
+    if hasattr(collector, "fspath") and \
+       str(collector.fspath).endswith(".ipynb"):
+        collector.skip_compare += ('text/latex', 'stderr')