fwupd: add testing tag to dummy plugin

Add an additional testing tag to dummy plugin. This testing tag is now
required for every firmware update under fwupd

BUG=b:292102739
TEST=fwupdmgr get-releases

Change-Id: I5166904a215ebd23e8bfea0b42024d2afc6b45ab
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/4704175
Reviewed-by: Daniel Campello <campello@chromium.org>
Commit-Queue: Rishabh Agrawal <rishabhagr@chromium.org>
Tested-by: Rishabh Agrawal <rishabhagr@chromium.org>
Reviewed-by: Tim Bain <tbain@google.com>
1 file changed