iterative_jump contains unused iterator result

[braingram]

The iterator returned by range(ndiffs) is unused (violating B007).

stcal/src/stcal/jump/twopoint_difference.py

Line 238 in 8cbe0a3

for i in range(ndiffs): # Can't have more than ndiffs CRs per pixel!

This may be expected (since cr_pix is recomputed during the loop) but it's unclear why range(ndiffs) is used. If the current behavior is as expected it seems worth remomving the noqa and assigning to _ instead of i.