Fix FutureWarning
Fix FutureWarning

```
fontbakery/Lib/fontbakery/checkrunner.py:410: FutureWarning: The behavior of this method will change in future versions. Use specific 'len(elem)' or 'elem is not None' test instead.
    if all(not x for x in args.values()):
```

googlefonts/fontbakery,googlefonts/fontbakery,googlefonts/fontbakery