fix(GUI): automatically rename the date column of ObsDF

Refs #38
1 job for 38-allow-any-date-column-name-for-the-obsdf-argument-of-the-shinygr-function in 2 minutes and 39 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Check
passed check_as_cran_patched #176997

00:02:39