v1.2.13: Make Bedrock embedding credentials optional and add IAM support

Features

• Make Bedrock embedding credentials optional and add IAM support
  • AWS credentials (aws_access_key_id, aws_secret_access_key) are now optional, defaulting to None
  • Added access_method field supporting "credentials" (explicit keys) and "iam" (AWS credential chain)
  • Added endpoint_url field for custom Bedrock endpoints
  • Enhanced validation logic for different authentication methods
  • Use BEDROCK_REGION_NAME env var for region, fallback to AWS defaults
  • Maintains full backwards compatibility with existing configurations

What's Changed

• Make Bedrock embedding credentials optional with IAM support
• Add custom endpoint URL support for Bedrock
• Improve region handling with environment variable priority
• Clean up unused dependencies and fix linting issues
• Version bump to 1.2.13 with updated changelog