S3 listings do not include meaningful timestamps

[brianaydemir]

This issue comes by way of PelicanPlatform/pelican#2295:

From the viewpoint of the Pelican client, listings from an S3 origin do not include meaningful timestamps (somewhere, we end up defaulting to the zero-value of UNIX epoch time):

[local:~]$ pelican object ls -l osdf://nsdf/testing/
/nsdf/testing/README.txt          225          1970-01-01 00:00:00
/nsdf/testing/empty.txt           0            1970-01-01 00:00:00

Querying the S3 object store via the AWS CLI indicates that there are meaningful timestamps to be had:

[local:~]$ ./aws.sh s3 ls s3://nasa-ecco/testing/
2025-04-23 10:15:32        225 README.txt
2025-05-05 13:49:48          0 empty.txt