fix(runtime): fix ambiguous use of init log error

[luke-h1]

When compiling with Swift 6.0+, the build fails with an "ambiguous use of 'init'" error in LambdaRuntime.swift. I have created a minimal reproduction repo that is available here: https://github.com/luke-h1/lambda-logger-reproduction

I've seen this occur in the following evenironments

• Swift version: 6.0 / 6.2
• swift-aws-lambda-runtime version: 2.4.0
• swift-log version: 1.6.0+
• Platform: macOS 15 / Amazon Linux 2

Issue #

N/A - This is a new issue I came across when trying to convert my lambda function to Swift

Description of changes

Logger.Level has two failable initializers that both accept a String:

• init?(rawValue: String)
• init?(_ description: String)

When using flatMap(Logger.Level.init), Swift 6's stricter type inference cannot disambiguate which initializer to use, resulting in this error:

.build/checkouts/swift-aws-lambda-runtime/Sources/AWSLambdaRuntime/LambdaRuntime.swift:50:69: error: ambiguous use of 'init'
 48 |         // use the LOG_LEVEL environment variable to set the log level.
 49 |         // if the environment variable is not set, use the default log level from the logger provided
 50 |         log.logLevel = Lambda.env("LOG_LEVEL").flatMap(Logger.Level.init) ?? logger.logLevel
    |                                                                     `- error: ambiguous use of 'init'
 51 | 
 52 |         self.logger = log

I'm a little new to Swift so if there's anything I need to do around accounting for previous versions of swift please let me know and I will add to this PR 👍

New/existing dependencies impact assessment, if applicable

No new dependencies were added to this change.

Conventional Commits

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[sebsto]

Thank you @luke-h1
Closing this PR in favour of that one #619
(it also fixes the mock server used for testing)