Update changelog for 7.7.4
Update changelog for 7.7.4

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