Adding other codeowners.

[gabrieldemarmiesse]

- What I did
I added other codeowners.

- How I did it
I got them from itssue #415

- How you can verify it

The tests are passing.

[titu1994]

Could you add me to the list as discussed in PR #415 as well ?

[gabrieldemarmiesse]

Could you give the list of features? We discussed quite some things and I don't want to make a mistake.

[titu1994]

Sure. They are:

• all applications other than ResNet
• callbacks/snapshot: entire module
• layers/convolution: SubPixelUpscaling
• layers/normalization: GroupNormalization

[gabrieldemarmiesse]

Thanks! I'll split the convolution and normalization modules and then add you as the codeowner.

[titu1994]

Thanks !