WINDSOR, Ontario — Canadian authorities were forcing crowds to disperse at the Ambassador Bridge after announcing Saturday morning they had started enforcing a judge’s injunction on the bridge blockade that has crippled the border for days. At about 9:45 a.m., semitrailers began to move away from the area and several protesters also appeared to choose to leave as authorities began to march toward the crowd. At about 10:55 a.m. the Windsor Police Department tweeted that people in the demonstration area are subject to arrest and advised them to leave immediately. Law enforcement officers move in…