build: update to rust 1.84.0

[grant0417]

Issue #, if available:

Description of changes:

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[grant0417]

The tests are failing due to an ICE in the compiler (rust-lang/rust#135235). Will wait for tomorrow to merge.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 13.69863% with 63 lines in your changes missing coverage. Please review.

Project coverage is 12.43%. Comparing base (fcd4003) to head (1c7acd0).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/fig_desktop/src/main.rs	0.00%	43 Missing ⚠️
crates/figterm/src/main.rs	0.00%	3 Missing ⚠️
crates/zbus/src/message/field.rs	0.00%	0 Missing and 3 partials ⚠️
crates/fig_desktop/src/platform/macos.rs	0.00%	2 Missing ⚠️
crates/shell-color/src/lib.rs	0.00%	2 Missing ⚠️
crates/alacritty_terminal/src/ansi.rs	50.00%	1 Missing ⚠️
crates/fig_auth/src/builder_id.rs	0.00%	0 Missing and 1 partial ⚠️
crates/fig_desktop/src/protocol/icons.rs	0.00%	1 Missing ⚠️
crates/fig_desktop/src/remote_ipc/mod.rs	0.00%	1 Missing ⚠️
crates/fig_desktop/src/utils.rs	0.00%	1 Missing ⚠️
... and 5 more

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #394       +/-   ##
===========================================
- Coverage   16.06%   12.43%    -3.63%     
===========================================
  Files         175     2233     +2058     
  Lines       16077   189905   +173828     
  Branches      665   174493   +173828     
===========================================
+ Hits         2582    23608    +21026     
- Misses      13495   165116   +151621     
- Partials        0     1181     +1181     

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