Removed conversion from Example to dict in BootstrapFewShotWithOptuna that breaks template line

[bendavidsteel]

BootstrapFewShotWithOptuna currently converts demostration examples to dicts, which breaks line 210 in template_v2.py as augmented cannot be accessed as an attribute. I tried converting to dotdict at the line instead, but dotdict demos seem to converted to just dicts later on, which therefore would require a more complicated fix.