Upgrade alpha_vantage to 2.0.0

[fabaff]

Description:

Commit log: https://github.com/RomelTorres/alpha_vantage/commits/develop

Example entry for configuration.yaml (if applicable):

sensor:
  - platform: alpha_vantage
    api_key: !secret av_api
    symbols:
      - name: Google
        currency: USD
        symbol: GOOGL
    foreign_exchange:
      - from: BTC
        to: USD
        name: Bitcoin

Checklist:

• The code change is tested and works locally.

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

• Local tests with tox run successfully. Your PR cannot be merged unless tests pass
• New dependencies have been added to the REQUIREMENTS variable ([example][ex-requir]).
• New dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.