♲ Populate request stats from connection directly

Previously, the data was accessed through `self` which generated
unnecessarily long lines.

cheroot/workers/threadpool.py

@@ -142,9 +142,9 @@ def _process_connections_until_interrupted(self):
                 else:
                     conn.close()
                 if is_stats_enabled:
-                    self.requests_seen += self.conn.requests_seen
-                    self.bytes_read += self.conn.rfile.bytes_read
-                    self.bytes_written += self.conn.wfile.bytes_written
+                    self.requests_seen += conn.requests_seen
+                    self.bytes_read += conn.rfile.bytes_read
+                    self.bytes_written += conn.wfile.bytes_written
                     self.work_time += time.time() - self.start_time
                     self.start_time = None
                 self.conn = None