Use the built-in importlib.metadata library in Python 3.8+ (#36225)

importlib_metadata is a backport of this library for Python 3.7 and
older.

homeassistant/package_constraints.txt

@@ -13,7 +13,7 @@ defusedxml==0.6.0
 distro==1.5.0
 hass-nabucasa==0.34.6
 home-assistant-frontend==20200613.0
-importlib-metadata==1.6.0
+importlib-metadata==1.6.0;python_version<'3.8'
 jinja2>=2.11.1
 netdisco==2.7.0
 pip>=8.0.3

homeassistant/util/package.py

@@ -8,9 +8,19 @@ import sys
 from typing import Optional
 from urllib.parse import urlparse
 
-from importlib_metadata import PackageNotFoundError, version
 import pkg_resources
 
+if sys.version_info[:2] >= (3, 8):
+    from importlib.metadata import (  # pylint: disable=no-name-in-module,import-error
+        PackageNotFoundError,
+        version,
+    )
+else:
+    from importlib_metadata import (  # pylint: disable=import-error
+        PackageNotFoundError,
+        version,
+    )
+
 _LOGGER = logging.getLogger(__name__)
 
 

requirements_all.txt

@@ -6,7 +6,7 @@ attrs==19.3.0
 bcrypt==3.1.7
 certifi>=2020.4.5.1
 ciso8601==2.1.3
-importlib-metadata==1.6.0
+importlib-metadata==1.6.0;python_version<'3.8'
 jinja2>=2.11.1
 PyJWT==1.7.1
 cryptography==2.9.2

setup.py

@@ -39,7 +39,7 @@ REQUIRES = [
     "bcrypt==3.1.7",
     "certifi>=2020.4.5.1",
     "ciso8601==2.1.3",
-    "importlib-metadata==1.6.0",
+    "importlib-metadata==1.6.0;python_version<'3.8'",
     "jinja2>=2.11.1",
     "PyJWT==1.7.1",
     # PyJWT has loose dependency. We want the latest one.