Region is needed when using custom s3 endpoint

[kkettinger]

Currently testing out the hetzner object storage beta with this config:

[repository]
repository = "opendal:s3"
password = "XXX"

[repository.options]
access_key_id = "XXX"
secret_access_key = "XXX"
bucket = "bucket-name"
root = "/"
endpoint = "https://fsn1.your-objectstorage.com"
# region = "us-east-1"

When not using region, opendal fails:

error: backend openDAL Backend cannot be loaded: ConfigInvalid (permanent) at Builder::build, context: { service: s3 } => region is missing. Please find it by S3::detect_region() or set them in env.

When commenting out the region key, it works.