Fix bug in `add_listing_col` when specifying a function and a format

[edelarua]

Closes #179

[github-actions[bot]]

Code Coverage Summary

Filename                 Stmts    Miss  Cover    Missing
---------------------  -------  ------  -------  ----------------------------------------------------
R/paginate_listing.R        47       1  97.87%   101
R/rlistings_methods.R      101      14  86.14%   39, 54, 58, 140-143, 146, 230-236
R/rlistings.R              166      25  84.94%   158-161, 164-167, 206-210, 374-377, 381-384, 417-420
TOTAL                      314      40  87.26%

Diff against main

Filename         Stmts    Miss  Cover
-------------  -------  ------  -------
R/rlistings.R       -1      -1  +0.51%
TOTAL               -1      -1  +0.28%

Results for commit: b83c44ba0fa1cdb38298da5a8c3b074a9d5f1c4b

Minimum allowed coverage is 80%

:recycle: This comment has been updated with latest results

[github-actions[bot]]

Unit Tests Summary

  1 files    4 suites   7s :stopwatch: 32 tests 25 :heavy_check_mark: 7 :zzz: 0 :x: 80 runs  71 :heavy_check_mark: 9 :zzz: 0 :x:

Results for commit b83c44ba.