build: update Rust toolchain version to 1.94.0 (apache#21045)

## Which issue does this PR close?

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- Closes apache#21040 .

## Rationale for this change

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in the issue then this section is not needed.
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just an update of the rust toolchain

## What changes are included in this PR?

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PR.
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solved some clippy warnings

## Are these changes tested?

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NA

## Are there any user-facing changes?

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no

Author: dariocurr

datafusion/core/src/datasource/file_format/csv.rs

@@ -114,6 +114,8 @@ mod tests {
             let len = bytes.len() as u64;
             let range = 0..len * self.max_iterations;
             let arc = self.iterations_detected.clone();
+            #[expect(clippy::result_large_err)]
+            // closure only ever returns Ok; Err type is never constructed
             let stream = futures::stream::repeat_with(move || {
                 let arc_inner = arc.clone();
                 *arc_inner.lock().unwrap() += 1;

datafusion/core/tests/sql/path_partition.rs

@@ -735,6 +735,8 @@ impl ObjectStore for MirroringObjectStore {
                     .map(|mut x| x.next().is_some())
                     .unwrap_or(false);
 
+                #[expect(clippy::result_large_err)]
+                // closure only ever returns Ok; Err type is never constructed
                 filter.then(|| {
                     Ok(ObjectMeta {
                         location,

rust-toolchain.toml

@@ -19,5 +19,5 @@
 # to compile this workspace and run CI jobs.
 
 [toolchain]
-channel = "1.93.0"
+channel = "1.94.0"
 components = ["rustfmt", "clippy"]