Update aws-crt-cpp to get mqtt-reconnect-timeout fixes (#49)

Author: graebm

setup.py

@@ -23,7 +23,7 @@
     url='https://github.com/aws/aws-iot-device-sdk-python-v2',
     packages = ['awsiot'],
     install_requires=[
-        'awscrt==0.5.12',
+        'awscrt==0.5.13',
         'futures;python_version<"3.2"',
         'typing;python_version<"3.5"',
     ],