refactor: Bump MSRV to 1.75 for async in trait

[Xuanwo]

Rust 1.75 was released six months ago and introduced great features such as async in trait. Many of our dependencies, including #2202, are adopting this feature. Let's update our MSRV to 1.75.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 9 lines in your changes missing coverage. Please review.

Project coverage is 42.72%. Comparing base (0cc0c62) to head (d7d2d8e).
Report is 48 commits behind head on main.

Files	Patch %	Lines
src/compiler/nvcc.rs	0.00%	2 Missing ⚠️
src/compiler/nvhpc.rs	0.00%	2 Missing ⚠️
src/compiler/rust.rs	75.00%	1 Missing and 1 partial ⚠️
src/compiler/tasking_vx.rs	0.00%	2 Missing ⚠️
src/compiler/diab.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2203       +/-   ##
===========================================
+ Coverage   30.91%   42.72%   +11.81%     
===========================================
  Files          53       53               
  Lines       20112    20428      +316     
  Branches     9755     9750        -5     
===========================================
+ Hits         6217     8728     +2511     
- Misses       7922     7975       +53     
+ Partials     5973     3725     -2248     

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[sylvestre]

LGTM, thanks