Ensure LOG_LEVEL is correctly picked up (#435)

Fix issue #434

Sources/AWSLambdaRuntimeCore/LambdaRuntime.swift

@@ -39,7 +39,8 @@ public final class LambdaRuntime<Handler>: @unchecked Sendable where Handler: St
         // this approach is less flexible but more performant than reading the value of the environment variable at each invocation
         var log = logger
         log.logLevel = Lambda.env("LOG_LEVEL").flatMap(Logger.Level.init) ?? .info
-        self.logger = logger
+        self.logger = log
+        self.logger.debug("LambdaRuntime initialized")
     }
 
     public func run() async throws {