psycopg2==2.6.2 insteadof 2.6 to be used for windows and python>=3.5

[NakitaOza]

In the requirements.txt, it is mentioned that we need to use psycopg2 verison 2.6

psycopg2==2.6

And we need to use Python 3.x

Make sure to install Python 3.x instead of the default 2.x

For python 3.5, the default compiler was changed to MSVC 2015.

In this scenario, the issue is that, for windows, we cannot use psycopg2==2.6, it doesn't compile, according to psycopg/psycopg2#350
(https://github.com/psycopg/psycopg2/pull/350)

The solution is to use psycopg2 version 2.6.2

I can fix this in the requirements.txt
I can send a PR for this, let me know what you think about this.

Thanks :)