while developing on localstack found out that the python version used is 2.7, while the docker-image uses version 3.6.8

as in the readme file I brought up my environment using:
```
make install
make infra
```
this will cause issues when touching parts different in these 2 major versions.

workaround:
```
make reinstall-p3
```
this changed the python version to 3.7.3 on debian 10, which is again above docker-image version...
import json
import uuid
import hashlib
from flask import Flask, jsonify, request, make_response
from localstack.services import generic_proxy
from localstack.utils.aws import aws_stack
from localstack.utils.common import to_str, to_bytes
from localstack.utils.analytics import event_publisher
APP_NAME = 'ddb_streams_api'
app = Flask(APP_NAME)
DDB_STREAMS = {}
DDB_KINESIS_STREAM_NAME_PREFIX = '__ddb_stream_'
ACTION_HEADER_PREFIX = 'DynamoDBStreams_20120810'
SEQUENCE_NUMBER_COUNTER = 1
def add_dynamodb_stream(table_name, latest_stream_label=None, view_type='NEW_AND_OLD_IMAGES', enabled=True):