Lionel Messi has been accused of breaching MLS rules after firing Inter Miami to glory in the Supporters’ Shield earlier this week. The Argentina international netted twice as his side beat Columbus Crew, with Messi picking up his second trophy over in the United States. After the victory, Messi and his Inter Miami team-mates surrounded the shield in their dressing room. One image shared on social media showed the veteran with a bottle of his Mas+ sports drink in one hand as he enjoyed the celebrations. This, however, has raised eyebrows. Given the MLS’s corporate sponsors is rival drinks bran…