Fix data race error in 'networking_test' package

Implement 'io.Stringer' for 'Session' struct.
Data race happens because 'clientHandler' mock in 'TestSessionTimeoutOnHandshake' test
reads 'Session' structure at the same time as 'clientSession.Close' call.

pkg/networking/session.go

@@ -6,6 +6,7 @@ import (
 	"context"
 	"encoding/base64"
 	"errors"
+	"fmt"
 	"io"
 	"log/slog"
 	"net"
@@ -85,6 +86,10 @@ func newSession(ctx context.Context, config *Config, conn io.ReadWriteCloser, tp
 	return s, nil
 }
 
+func (s *Session) String() string {
+	return fmt.Sprintf("Session{local=%s,remote=%s}", s.LocalAddr(), s.RemoteAddr())
+}
+
 // LocalAddr returns the local network address.
 func (s *Session) LocalAddr() net.Addr {
 	if a, ok := s.conn.(addressable); ok {