Update the aws-py-voting-app

[staeff]

I was testing the aws-py-voting-app and ran into two issues.

1. The docker file building process timed out. I pinned tiangolo/uwsgi-nginx-flask:latest and afterwards it worked for me
2. I received this errormessage on the deploy:

aws:lb:TargetGroup (redis-targetgroup):
    error: 1 error occurred:
        * creating urn:pulumi:dev::voting-app::aws:lb/targetGroup:TargetGroup::redis-targetgroup: 1 error occurred:
        * error modifying Target Group Attributes: ValidationError: 'Stickiness type' must be one of [app_cookie, lb_cookie, source_ip]
        status code: 400, request id: 9995a158-8d9b-4e97-93ed-884389a95f6d

Resources:
    + 17 created

Duration: 45m20s

Changing lb_cookie with source_ip in the stickiness configuration fixed it.

[github-actions[bot]]

PR is now waiting for a maintainer to run the acceptance tests.

Note for the maintainer: To run the acceptance tests, please comment /run-example-tests on the PR