fix: Resolve Rust CI workflow issues

- Remove unused PixelFormat import in capture_grab.rs
- Simplify device_index selection logic in capture_callback.rs
- Remove unnecessary type cast (device_index as i32)
- Add cache: false to Rust toolchain setup to avoid Cargo.toml lookup errors

Fixes clippy warnings:
- unused-imports
- if-same-then-else
- unnecessary-cast

Author: wysaid

.github/workflows/rust.yml

@@ -57,6 +57,7 @@ jobs:
       with:
         toolchain: stable
         components: clippy, rustfmt
+        cache: false
 
     # Build C++ Library (Linux/macOS)
     # We build in build/Debug to match build.rs expectations for Unix Makefiles
@@ -121,8 +122,7 @@ jobs:
       uses: actions-rust-lang/setup-rust-toolchain@v1
       with:
         toolchain: stable
-
-    # Note: We intentionally DO NOT build the C++ library manually here.
+        cache: false
     # The build.rs script should handle it via the 'build-source' feature.
 
     - name: Build Rust bindings (Source)

bindings/rust/examples/capture_callback.rs

@@ -27,14 +27,10 @@ fn main() -> Result<()> {
     }
 
     // Select camera device (automatically use first device for testing)
-    let device_index = if devices.len() == 1 {
-        0
-    } else {
-        0 // Just use first device for now
-    };
+    let device_index = 0;
 
     // Create provider with selected device
-    let mut provider = Provider::with_device(device_index as i32)?;
+    let mut provider = Provider::with_device(device_index)?;
 
     // Set camera properties
     let requested_width = 1920;

bindings/rust/examples/capture_grab.rs

@@ -1,4 +1,4 @@
-use ccap::{LogLevel, PixelFormat, PropertyName, Provider, Result, Utils};
+use ccap::{LogLevel, PropertyName, Provider, Result, Utils};
 use std::fs;
 
 fn main() -> Result<()> {