Broken when exc_info argument is provided to the log() method

Broken on Python 3.8 ig.

Minimal code to reproduce (assuming Python 3.8):
```
import picologging as logging


logger = logging.getLogger()
logger.log(logging.WARN, "Hello", exc_info=False)
```

Error I get:
```
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: print_exception() missing 2 required positional arguments: 'value' and 'tb'
```