Increase attachment size.

I love using Pushover with my Reolink cameras but with a max of 2.5mb attachment size, I can't use the app with my Duo 2. The Duo 2 is basically two cameras in one so the file size is around 5mb. Not sure if the actual image size is an issue or not, but just incase, mine are 4096x1536.

I have seen other people on reddit have the same issue with the newer 12mp cameras too so I am sure they would also like the change.