[Feature Request] Add ligatures for bitwise-shift-assignment operators (<<= and >>=)

[jiyometrik]

Description

Cascadia Code already has ligatures for bitwise-shift left and right operators (<< and >>, see image), and I feel that the font could be improved by adding the assignment operators for the bitwise-shift operations (i.e. <<= and >>=). This would benefit developers who are working with low- or mid- level languages (e.g. C, C++) who have the opportunity to work with bitwise operations.

[aaronbell]

Ligatures for these characters have been created (see #435 ) and should be available worth the next release.