An investigator who alleges he was fired from Chicago’s Independent Police Review Authority for refusing to clear an officer in the shooting death of a suspected carjacker does not have a claim under the First Amendment, a federal appeals court held Tuesday.The 7th U.S. Circuit Court of Appeals declined to revive a lawsuit Lorenzo Davis filed accusing two top officials of the now-defunct review authority of violating his right to free speech.The authority was replaced by the Civilian Office of Police Accountability …