Fix "Cannot access Disposed Object" exception when accessing HttpClient in GitHubWebHook AWS Lambda Function

[johnt84]

When the GitHub Web Hook AWS Lambda Function is first called then the expected result is returned but if the GitHub Web Hook AWS Lambda Function is called again within a short time (i.e. 15 mins) then "Cannot access Disposed Object" exception is raised when trying to access the HttpClient.

Have asked this question as a discussion on the AWS Lambda Dotnet repo