Add pyupgrade (in pre-commit and CI) (#33688)

* Add pyupgrade (in pre-commit and CI)

* Fix leftover results of pyupgrade

* Ensure we run for Python 3.7 on pyupgrade

docs/source/conf.py

@@ -1,5 +1,4 @@
 #!/usr/bin/env python3
-# -*- coding: utf-8 -*-
 #
 # Home-Assistant documentation build configuration file, created by
 # sphinx-quickstart on Sun Aug 28 13:13:10 2016.
@@ -26,7 +25,7 @@ from homeassistant.const import __short_version__, __version__
 PROJECT_NAME = 'Home Assistant'
 PROJECT_PACKAGE_NAME = 'homeassistant'
 PROJECT_AUTHOR = 'The Home Assistant Authors'
-PROJECT_COPYRIGHT = ' 2013-2020, {}'.format(PROJECT_AUTHOR)
+PROJECT_COPYRIGHT = f' 2013-2020, {PROJECT_AUTHOR}'
 PROJECT_LONG_DESCRIPTION = ('Home Assistant is an open-source '
                             'home automation platform running on Python 3. '
                             'Track and control all devices at home and '
@@ -37,7 +36,7 @@ PROJECT_GITHUB_REPOSITORY = 'home-assistant'
 
 GITHUB_PATH = '{}/{}'.format(
     PROJECT_GITHUB_USERNAME, PROJECT_GITHUB_REPOSITORY)
-GITHUB_URL = 'https://github.com/{}'.format(GITHUB_PATH)
+GITHUB_URL = f'https://github.com/{GITHUB_PATH}'
 
 
 sys.path.insert(0, os.path.abspath('_ext'))
@@ -132,7 +131,7 @@ def linkcode_resolve(domain, info):
 
     fn = fn[index:]
 
-    return '{}/blob/{}/{}{}'.format(GITHUB_URL, code_branch, fn, linespec)
+    return f'{GITHUB_URL}/blob/{code_branch}/{fn}{linespec}'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.