Update year in copyright comments

[BronyDust]

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• [X] I've followed the contributing guidelines to the best of my understanding
• [X] I've read and understood the contributing guidelines
• [X] I've formatted my code according to Natron's code style
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PR Description

What type of PR is this? (Check one of the boxes below)

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [X] Improvement (non-breaking change which does not add functionality nor fixes a bug but improves Natron in some way)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] My change requires a change to the documentation
  • [ ] I have updated the documentation accordingly

What does this pull request do?

I just updated year in copyright messages across the app (comments and UI). Thied not to change patch logs or something. But it needs to be rechecked.