Resolve SNS topic ARNs via STS + SNS.GetTopicAttributes before using SNS.CreateTopic

[kalaspuff]

Summary

Publishing through the AWS SNS+SQS transport no longer assumes sns:CreateTopic is available. The transport first tries to resolve the topic ARN by calling sts:GetCallerIdentity (for the account ID) and sns:GetTopicAttributes on the constructed ARN, caches the result, and only then falls back to the existing sns:CreateTopic path (including topic attributes) when lookup does not find a topic.

Why

Deployments that cannot grant sns:CreateTopic but can publish to an already-provisioned topic (with typical STS identity and SNS read permissions) should be able to publish without failing on create topic.

Added Option

Options now include aws_endpoint_urls.sts for configuring the AWS STS endpoint (for example with Localstack).

If a custom endpoint is set for aws_endpoint_urls.sns but not for aws_endpoint_urls.sts, the STS client falls back to the SNS endpoint URL for backward compatibility with existing configurations.

Implementation notes

• New helpers: get_topic_arn, _lookup_topic_arn_via_sts_and_sns, and _sns_client_error_indicates_missing_topic (handles missing-topic ClientError shapes).
• Lookup uses the same SNS topic create condition/lock pattern as create_topic so concurrent callers stay consistent with cached cls.topics.
• Retries (up to 3) for transient STS/SNS/network/timeout issues; missing topic returns None so publish can still attempt create_topic when permitted.
• create_client("sts", …) is wired in the SNS+SQS transport and in ClientConnector overloads for typed STS usage.
• Dev typing: types-aiobotocore extras include sts; lockfile picks up types-aiobotocore-sts and related resolution changes.

Python 3.9 deprecation

Dropped support for Python 3.9.

[codecov]

Codecov Report

❌ Patch coverage is 68.46847% with 35 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.77%. Comparing base (3aa881b) to head (bc3758c).
⚠️ Report is 15 commits behind head on master.

Files with missing lines	Patch %	Lines
tomodachi/transport/aws_sns_sqs.py	66.33%	34 Missing ⚠️
tomodachi/helpers/aiobotocore_connector.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2077      +/-   ##
==========================================
- Coverage   73.91%   73.77%   -0.14%     
==========================================
  Files          53       53              
  Lines        8112     8222     +110     
==========================================
+ Hits         5996     6066      +70     
- Misses       2116     2156      +40     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.