Updates checksums for WBFL KGO

[MoseleyS]

Following #1956

The above PR had an associated change to acceptance test data (https://github.com/metoppv/improver_test_data/pull/35), but the checksums were not updated, and the testing was insufficient (my fault! sorry).

This PR updates the checksum for the modified file.

Testing:

• [x] Ran tests and they passed OK
• [x] Added new tests for the new feature(s)

[codecov[bot]]

Codecov Report

All modified lines are covered by tests :white_check_mark:

Comparison is base (2520f58) 98.39% compared to head (a6b3478) 98.39%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1957 +/- ## ======================================= Coverage 98.39% 98.39% ======================================= Files 123 123 Lines 11814 11814 ======================================= Hits 11624 11624 Misses 190 190 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.