checks: Removes unnecessary braces

[brooksprumo]

Problem

When upgrading nightly Rust¹, there was a CI checks error²:

warning: unnecessary braces around block return value
  --> program-runtime/src/invoke_context.rs:63:21
   |
63 |                     $inner
   |                     ^^^^^^
   |
   = note: `#[warn(unused_braces)]` on by default
warning: `solana-program-runtime` (lib test) generated 1 warning

Summary of Changes

Remove the braces.

Footnotes

1. https://github.com/solana-labs/solana/pull/34673 ↩

2. https://buildkite.com/solana-labs/solana/builds/106341#018ce4f8-f32b-4356-92e3-b6e12960a147 ↩

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (871355a) 81.8% compared to head (ab584a3) 81.8%.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #34681     +/-   ##
=========================================
- Coverage    81.8%    81.8%   -0.1%     
=========================================
  Files         824      824             
  Lines      222687   222687             
=========================================
- Hits       182298   182296      -2     
- Misses      40389    40391      +2     

[brooksprumo]

@Lichtso Let me know if you'd prefer a different fix for the warning. E.g. an #[allow(unused_braces)].

I feel like this warning isn't good because it makes the resulting code look strange, so I'm very open to alternative resolutions.

[Lichtso]

Its a macro, so this seems acceptable as is.