Hello it is small improvement for Route53 (dns_aws)

Description:

• Introduces a simple retry mechanism in aws_rest() with exponential backoff for AWS Route53 throttling errors (Throttling, RequestThrottled, RateLimit, or Rate exceeded).
• No other changes have been made, and the existing logic is preserved.
• Ensures that acme.sh can gracefully handle rate-limited requests to Route53 instead of failing immediately.

Why:

• When Route53 is under heavy load, AWS may respond with a throttling error. Without retries, the request fails and the certificate issuance is disrupted.
• This backoff approach retries the request up to five times, doubling the wait each time, allowing enough time for Route53 to recover from throttling.

How:

• Added a while loop in aws_rest() with a maximum of five attempts (max_retries=5).
• On each throttling error, we sleep for exponentially longer intervals (_sleep_time = base_sleep * 2^(attempt-1)).
• If throttling persists beyond the maximum attempts, we return an error to maintain backward compatibility.

Testing:

• Manually tested by simulating throttling responses. Verified that the script retries and succeeds once AWS is ready to accept requests again.

Thank you for reviewing!