Post caching issue

[ktnk-dev]

Description

During teleview.getChannel via telegram provider last 20 posts become cached. Found in telegram.py:106 and telegram.py:113

Issue

New posts cannot be loaded via channel.getPosts because of caching (telegram.py:117)

For example

import teleview

teleview.setProvider(teleview.provider.telegram) 
channel = await teleview.getChannel('@durov')

oldPost = [posts async for posts in channel.getPosts(limit = 1)][0]
oldPost._iternal['id']
# -> some integer

Then @durov post new message

newPost = [posts async for posts in channel.getPosts(limit = 1)][0]
newPost._iternal['id']
# -> SAME integer as before