allow fetching latest binaries when using other endpoints/creds

when running under something like us-gov-east-1, the latest-binaries.sh
script fails b/c it tries to access the us-west-2 bucket from the wrong
endpoints.

specify the endpoint url to avoid these kinds of errors:

$ ./hack/latest-binaries.sh 1.29

An error occurred (AccessDenied) when calling the ListObjectsV2
operation: Access Denied

also, specify to perform an unauthenticated s3 api request b/c the
govcloud creds wouldn't work against the commercial cloud endpoints and
you end up with errors like:

$ ./hack/latest-binaries.sh 1.29

An error occurred (InvalidToken) when calling the ListObjectsV2 operation:
The provided token is malformed or otherwise invalid.

hack/latest-binaries.sh

@@ -13,7 +13,7 @@ MINOR_VERSION="${1}"
 
 # retrieve the available "VERSION/BUILD_DATE" prefixes (e.g. "1.28.1/2023-09-14")
 # from the binary object keys, sorted in descending semver order, and pick the first one
-LATEST_BINARIES=$(aws s3api list-objects-v2 --bucket amazon-eks --prefix "${MINOR_VERSION}" --query 'Contents[*].[Key]' --output text | cut -d'/' -f-2 | sort -Vru | head -n1)
+LATEST_BINARIES=$(aws s3api list-objects-v2 --bucket amazon-eks --prefix "${MINOR_VERSION}" --query 'Contents[*].[Key]' --output text --endpoint-url https://s3.us-west-2.amazonaws.com --no-sign-request | cut -d'/' -f-2 | sort -Vru | head -n1)
 
 if [ "${LATEST_BINARIES}" == "None" ]; then
   echo >&2 "No binaries available for minor version: ${MINOR_VERSION}"