setting values for iats_days is an array, not a string - gives a warning.

[adixon]

As noted by @totten here: https://test.civicrm.org/job/CiviCRM-Ext-Matrix/BKPROF=min,BUILDTYPE=git,CIVIVER=master,EXTKEY=com.iatspayments.civicrm,label=bknix-tmp/4830/testReport/(root)/CRM_Iats_SettingsTest/testGetDates/

CRM_Iats_SettingsTest::testGetDates
trim() expects parameter 1 to be string, array given

/home/homer/buildkit/build/build-0/web/sites/all/modules/civicrm/ext/com.iatspayments.civicrm/CRM/Iats/Utils.php:17
/home/homer/buildkit/build/build-0/web/sites/all/modules/civicrm/ext/com.iatspayments.civicrm/tests/phpunit/CRM/Iats/SettingsTest.php:56
/home/homer/buildkit/extern/phpunit9/phpunit9.phar:2307

[adixon]

Additional fix in d5eadb9