Update changelog for 7.15.2
Update changelog for 7.15.2

mParticle/mparticle-apple-sdk,mParticle/mparticle-apple-sdk,mParticle/mParticle-iOS-SDK,mParticle/mparticle-apple-sdk,mParticle/mParticle-iOS-SDK,mParticle/mparticle-apple-sdk,mParticle/mParticle-iOS-SDK,mParticle/mparticle-apple-sdk,mParticle/mparticle-apple-sdk