Related to https://github.com/mitchellh/ghostty/issues/1082
This fixes two separate issues to follow along with the new spec changes
Kovid pushed to Kitty:
1. When two modifiers are pressed and one is released, this shows up
as a proper release event with the correct side. Previously, the
correct side was shown but as a press event.
2. When two modifiers are pressed and one is released, the Kitty event
should not have that specific modifier set. For example, pressing
left ctrl, then right ctrl, then releasing right ctrl should encode
as "right ctrl released" but with NO modifiers still present.
9642dd3275