Avoid calling the deprecated "findAll" BeautifulSoup4 method

The latest release of BeautifulSoup4 (4.13.0, released yesterday) has started
to emit DeprecationWarnings when calling methods that have been marked as
deprecated for over a decade, and the deprecated methods are scheduled to be
removed in version 4.15.0:
https://git.launchpad.net/beautifulsoup/commit/?id=e9629a8aafc737578bd509ffc6b989ffedae7c41.

This changes the one call to `findAll` to instead be `find_all` to avoid
triggering a DeprecationWarning and to ensure the library keeps working with
newer versions of BeautifulSoup4.

Author: Tenzer

webtest/forms.py

@@ -432,7 +432,7 @@ def _parse_fields(self):
         fields = OrderedDict()
         field_order = []
         tags = ('input', 'select', 'textarea', 'button')
-        for pos, node in enumerate(self.html.findAll(tags)):
+        for pos, node in enumerate(self.html.find_all(tags)):
             attrs = dict(node.attrs)
             tag = node.name
             name = None