Update Rust toolchain from 1.85.0 to 1.86.0

Co-authored-by: simongdavies <1397489+simongdavies@users.noreply.github.com>
Signed-off-by: Simon Davies <simongdavies@users.noreply.github.com>

Author: Copilot

action.yml

@@ -5,9 +5,9 @@ description: "Common setup steps for GitHub workflows in the Hyperlight project"
 
 inputs:
   rust-toolchain:
-    description: "(Default: 1.85.0) Rust toolchain specification to install - see https://rust-lang.github.io/rustup/concepts/toolchains.html#toolchain-specification"
+    description: "(Default: 1.86.0) Rust toolchain specification to install - see https://rust-lang.github.io/rustup/concepts/toolchains.html#toolchain-specification"
     required: false
-    default: "1.85.0"
+    default: "1.86.0"
 
 runs:
   using: composite