embedded http client user-agent string should include library version

[tomerd]

#98 (comment)

[weissi]

this is my SwiftPM feature request to allow this: https://bugs.swift.org/browse/SR-12926

[sebsto]

Not fixed as of today
https://github.com/swift-server/swift-aws-lambda-runtime/blob/main/Sources/AWSLambdaRuntimeCore/LambdaRuntimeClient.swift#L137

@weissi any idea if SR-12926 will be adopted ?