Fix segmentation_kwargs regression in AnchorImage

[jklaise]

Addresses #580.

[codecov]

Codecov Report

Merging #581 (546161b) into master (9089f2a) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #581      +/-   ##
==========================================
- Coverage   82.06%   82.05%   -0.02%     
==========================================
  Files          77       77              
  Lines       10518    10517       -1     
==========================================
- Hits         8632     8630       -2     
- Misses       1886     1887       +1     

Impacted Files	Coverage Δ
alibi/explainers/anchor_image.py	93.12% <100.00%> (-0.05%)	⬇️
alibi/explainers/tests/test_anchor_image.py	97.97% <0.00%> (-1.02%)	⬇️