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")
@@ -26,7 +26,7 @@ args = parser.parse_args()
 #}
 #configure_logger(logstash_host=args.loghost,level=args.loglevel, log_extra=log_extra)
 logging.getLogger().setLevel(args.loglevel)
-git_hash=metadata("pypcc")["Summary"]
+git_hash=metadata.metadata("pypcc")["Summary"]
 logging.info("Git Hash="+git_hash)
 
 from pypcc.opcuaserv import opcuaserv