BTT 3.5" TFT E3 V3.0 does not fit the stock 12864 mount

[jon-harper]

I'm a little shocked about this, since the part should be a drop-in replacement. The CAD shows the same issue.

Reported via Discord.

[jon-harper]

https://github.com/jon-harper/OmniBox/tree/unstable/Panels/Display/BTT%203.5%20TFT%20E3

Fix for fit testing.

[jon-harper]

Mounts needs to expand by up to 1mm around the display to account for hand-soldering sloppiness.