Fix dumb mistake -- used 'not' where I wanted to catch error, not exclude it. Why did Python 3.6.6 not fail?

Author: kelseymh

easybuild/framework/easyconfig/easyconfig.py

@@ -587,7 +587,7 @@ def update(self, key, value, allow_duplicate=True):
             raise EasyBuildError(msg, key, value)
 
         # For dictionaries, input value cannot be a string; must be iterable
-        if isinstance(self[key], dict) and not isinstance(value, string_type):
+        if isinstance(self[key], dict) and isinstance(value, string_type):
             msg = "Can't update configuration value for %s, because the attempted"
             msg += "update value, '%s', is not iterable (list, tuple, dict)."
             raise EasyBuildError(msg, key, value)