Removes checksums for PNGs that should never have been added.

[MoseleyS]

IMPRO-1945 (#1390) included PNG files in the acceptance test directory. These have been manually removed, but are still present in the list of checksums causing the tests to fail on master. This ticket updates the checksums to remove these two PNG files.

Testing:

• Ran tests and they passed OK

[codecov]

Codecov Report

Merging #1399 (b90cc32) into master (9317703) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1399   +/-   ##
=======================================
  Coverage   96.35%   96.36%           
=======================================
  Files          89       89           
  Lines        7600     7614   +14     
=======================================
+ Hits         7323     7337   +14     
  Misses        277      277           

Impacted Files	Coverage Δ
improver/blending/weighted_blend.py	100.00% <0.00%> (ø)
improver/metadata/forecast_times.py	100.00% <0.00%> (ø)
improver/metadata/constants/mo_attributes.py	100.00% <0.00%> (ø)
improver/blending/calculate_weights_and_blend.py	98.61% <0.00%> (+0.06%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9317703...b90cc32. Read the comment docs.

[cgsandford]

Looks good to me - please go ahead and merge.