Remove usage of deprecated pkg_resource in favor of importlib.metadata

In setup.py just remove a check for a 2018+ release of setuptools.

Author: xrmx

elasticapm/__init__.py

@@ -28,6 +28,7 @@
 #  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 #  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 import sys
+import importlib.metadata
 
 from elasticapm.base import Client, get_client  # noqa: F401
 from elasticapm.conf import setup_logging  # noqa: F401
@@ -54,10 +55,7 @@
 _activation_method = None
 
 try:
-    try:
-        VERSION = __import__("importlib.metadata").metadata.version("elastic-apm")
-    except ImportError:
-        VERSION = __import__("pkg_resources").get_distribution("elastic-apm").version
+    VERSION = importlib.metadata.version("elastic-apm")
 except Exception:
     VERSION = "unknown"
 

setup.py

@@ -44,11 +44,8 @@
 import codecs
 import os
 
-import pkg_resources
 from setuptools import setup
 
-pkg_resources.require("setuptools>=39.2")
-
 
 def get_version():
     """