[Documentation] Add changelog for release 3.15.1. #21617

Job	Run time
External SlurmDBD Template Validation	42s
AWS Batch CLI Tests (ubuntu-latest, Code Checks AWS Batch CLI)	43s
AWS Batch CLI Tests (ubuntu-latest, Python 3.10 AWS Batch CLI Tests Coverage)	39s
API Model Validation	1m 36s
Dependency Check	35s
Shellcheck	4s
CLI Tests (ubuntu-latest, Python 3.9 Tests)	3m 46s
AWS Batch CLI Tests (ubuntu-latest, Python 3.11 AWS Batch CLI Tests)	38s
CLI Tests (ubuntu-latest, Code Checks)	1m 30s
AWS Batch CLI Tests (ubuntu-latest, Python 3.10 AWS Batch CLI Tests)	31s
CLI Tests (ubuntu-latest, Python 3.10 Tests Coverage)	6m 1s
CLI Tests (ubuntu-latest, Python 3.11 Tests)	2m 54s
CLI Tests (ubuntu-latest, CLI CloudFormation Templates Checks)	57s
AWS Batch CLI Tests (ubuntu-latest, Python 3.12 AWS Batch CLI Tests)	38s
CLI Tests (ubuntu-latest, API CloudFormation Templates Checks)	27s
CLI Tests (ubuntu-latest, Python 3.12 Tests)	3m 0s
AWS Batch CLI Tests (ubuntu-latest, Python 3.9 AWS Batch CLI Tests)	41s
CLI Tests (ubuntu-latest, Python 3.10 Tests)	3m 42s
CLI Tests (ubuntu-latest, Integration Tests Config Checks)	57s
	30m 1s

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