Fix decimal array display in iasWorld data test output workbooks

[jeancochrane]

Some of our iasWorld data tests query for arrays of decimals, particularly in the card and lline fields. When we output these values to Excel spreadsheets using the run_iasworld_data_tests script, the formatting looks quite strange:

Let's tweak run_iasworld_data_tests to fix this problem. This will likely require casting the decimals to some other data type like int or str before outputting them to the workbook.

To reproduce and examine the problem, run the following command in the dbt/ subdir:

python3 scripts/run_iasworld_data_tests.py iasworld_land_class_ex_matches_pardat_class_ex iasworld_dweldat_class_matches_pardat_class

Then, open up the workbook whose path the script prints to the console.