Update gitignore

[desertsagebrush]

Detailed description

Update the project gitignore to properly respect the meson deps folder and the appropriate wrap files/libopencm3. This is basically just Dragonmux's patch from Discord, but since I was poking at other stuff anyway, I figured that I would throw together a pull request for it.

Your checklist for this pull request

• I've read the Code of Conduct
• I've read the guidelines for contributing to this repository
• It builds for hardware native (see Building the firmware)
• It builds as BMDA (see Building the BMDA)
• I've tested it to the best of my ability
• My commit messages provide a useful short description of what the commits do

[dragonmux]

LGTM, merging. Thank you very much for the contribution!