Update ImageJ2 submodule for pom-scijava 1.51

APIs for SCIFIO and ImgLib2 changed with the version bumps inside
pom-scijava 1.51 (i.e., scifio 0.3.0 and imglib2 2.0.0-beta-9).
In order for the ImageJ2 code to build against those, it needed
to be updated as well.

These sorts of problems will go away once Fiji switches over
completely to release version couplings, since we will no longer
need submodules at all after that.