Use correct native importlib library available Python 3.7+

importlib_metadata is an external dependency that needs to be installed through pip / pypi.

The correct, native, library is known as importlib

This patch fixes a broken import.

pypcc/pypcc.py

-import logging
+from importlib import metadata
 import argparse
+import logging
+import signal
+import sys
 import threading
 import time
-import sys
-import signal
-from importlib_metadata import metadata
 
 parser = argparse.ArgumentParser()
 parser.add_argument("-s", "--simulator", help="Do not connect to I2c, but simulate behaviour.", action="store_true")