Looping through dates in shell script

loop-dates.sh

#!/bin/bash -l
# loop-dates.sh 2019-02-01 2019-03-01
start_time=`date +"%Y-%m-%d" -d $1`
end_time=`date +"%Y-%m-%d" -d $2`
dt=$start_time

while [ "$dt" != "$end_time" ] ;
do
    start=`date '+%Y-%m-%d %T' -d "$dt"`;
    end=`date '+%Y-%m-%d %T' -d "$dt +1 day"`;
    echo $start, $end
    python your-awesome-script.py --start_time="$start" --end_time="$end"
    dt=`date +"%Y-%m-%d" -d "$dt +1 day"`;
    sleep 1s
done