Fix Rendering of Left Double Fat Arrow <<=

[rajadain]

Current rendering of Left Double Fat Arrow <<= in Commit Mono:

Here's the correct rendering in Berkeley Mono:

Right Double Fat Arrow works correctly, although ideally there would be less space between the two angles:

Again, here is Berkeley Mono for comparison:

https://github.com/tonsky/FiraCode also supports these correctly.

[arjpar]

@eigilnikolajsen I can also reproduce this issue if you enable ss01 & ss02 (iirc). Are the sources for the font available anywhere? I couldn't find them in the repo.