Bump emitted FIRRTL to 3.3.0

Change the reported version of Chisel-emitted FIRRTL to 3.3.0.  Version
3.2.0 includes groups and Chisel is currently emitting things that are not
in a spec version yet, e.g., property lists.

Signed-off-by: Schuyler Eldridge <schuyler.eldridge@sifive.com>