patman: Fix tests if add_maintainers is set to False

If add_maintainers is set to False in the user's ~/.patman config, it will
cause the custom_get_maintainer_script to fail since that test expects
maintainers to be added. Set add_maintainer to True in the .patman config
to prevent this.

Fixes: 8c042fb7f9f ("patman: add '--get-maintainer-script' argument")
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/func_test.py b/tools/patman/func_test.py
index e391849..9c016fb 100644
--- a/tools/patman/func_test.py
+++ b/tools/patman/func_test.py
@@ -540,7 +540,8 @@
             with open('.patman', 'w', buffering=1) as f:
                 f.write('[settings]\n'
                         'get_maintainer_script: dummy-script.sh\n'
-                        'check_patch: False\n')
+                        'check_patch: False\n'
+                        'add_maintainers: True\n')
             with open('dummy-script.sh', 'w', buffering=1) as f:
                 f.write('#!/usr/bin/env python\n'
                         'print("hello@there.com")\n')