Exclude all test files from code coverage analysis

Previously test directories were only excluded from coverage analysis if
they were just under `astroquery` or separated from it by one directory,
but now all directories named `tests` are excluded no matter how deep in
the directory hierarchy they are.

Author: eerovaher

setup.cfg

@@ -99,13 +99,11 @@ exclude = _astropy_init.py,version.py,astroquery/template_module
 [coverage:run]
 omit =
   astroquery/*_init*
-  astroquery/tests/*
-  astroquery/*/tests/*
+  astroquery/**/tests/*
   astroquery/*setup*
   astroquery/version*
   */astroquery/*_init*
-  */astroquery/tests/*
-  */astroquery/*/tests/*
+  */astroquery/**/tests/*
   */astroquery/*setup*
   */astroquery/version*