Update praw to 6.4.0

[fabaff]

Description:

Changelog: https://github.com/praw-dev/praw/blob/master/CHANGES.rst#640-20190921

Example entry for configuration.yaml (if applicable):

sensor:
  - platform: reddit
    username: !secret reddit_username
    password: !secret reddit_password
    client_id: !secret reddit_client_id
    client_secret: !secret reddit_client_secret
    subreddits:
      - news
      - homeassistant

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.

If the code communicates with devices, web services, or third-party tools:

• [The manifest file][manifest-docs] has all fields filled out correctly ([example][ex-manifest]).
• New dependencies have been added to requirements in the manifest ([example][ex-requir]).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.

[fabaff]

Also, #27284

[balloob]

Because of moving it to the top of the file, it will also be needed to add to test deps in script/gen_requirements_all.py. I wonder if we should start generating that file automatically by reading the manifests of integrations that have tests.

[fabaff]

I wonder if we should start generating that file automatically by reading the manifests of integrations that have tests.

Sounds like a plan.

[balloob]

I've implemented and merged that in #27362

[djpremier]

Hey @fabaff, for correction tox tests (tests/components/reddit/test_sensor.py), insert: from homeassistant.components.reddit import sensor as reddit_sensor in the top-level, and with patch.object(reddit_sensor, 'praw', mock_praw): inside function test_setup_with_valid_config(), like this:

@MockDependency("praw")
@patch("praw.Reddit", new=MockPraw)
def test_setup_with_valid_config(self, mock_praw):
    """Test the platform setup with movie configuration."""
    with patch.object(reddit_sensor, 'praw', mock_praw):
        setup_component(self.hass, "sensor", VALID_CONFIG)

[fabaff]

@djpremier, thanks.