Update Rust to 1.90

https://blog.rust-lang.org/2025/09/18/Rust-1.90.0/

Author: mlafeldt

crates/duckdb/src/vtab/excel.rs

@@ -4,13 +4,15 @@ use super::{BindInfo, DataChunkHandle, InitInfo, LogicalTypeHandle, TableFunctio
 use crate::core::{Inserter, LogicalTypeId};
 use calamine::{open_workbook_auto, Data, DataType, Range, Reader};
 
+#[allow(dead_code)]
 #[repr(C)]
 struct ExcelBindData {
     range: Range<Data>,
     width: usize,
     height: usize,
 }
 
+#[allow(dead_code)]
 #[repr(C)]
 struct ExcelInitData {
     start: AtomicUsize,

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "1.89"
+channel = "1.90"
 components = ["rustfmt", "clippy"]