fix: remove duplicate prelude imports causing wasm32v1-none ambiguity

The redundant `use ::core::prelude::rust_2021::*;` was causing
ambiguity errors because `crate::lib::*` already imports `Some`,
`None`, `Option` via `crate_root.rs`.

This fixes cargo clippy/check failures on wasm32 targets.

Files fixed:
- serde_core/src/de/mod.rs
- serde_core/src/de/impls.rs
- serde_core/src/ser/mod.rs
- serde_core/src/ser/impls.rs
- serde_core/src/ser/fmt.rs
- serde_core/src/ser/impossible.rs
- serde_core/src/private/doc.rs

serde_core/src/de/impls.rs

@@ -1,11 +1,5 @@
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-// Even when "std" feature is enabled (due to Cargo feature unification),
-// the prelude may not be injected on wasm32v1-none target
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 use crate::de::{
     Deserialize, Deserializer, EnumAccess, Error, MapAccess, SeqAccess, Unexpected, VariantAccess,
     Visitor,

serde_core/src/de/mod.rs

@@ -114,10 +114,6 @@
 
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 ////////////////////////////////////////////////////////////////////////////////
 
 pub mod value;

serde_core/src/private/doc.rs

@@ -2,10 +2,6 @@
 
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 use crate::ser;
 
 #[doc(hidden)]

serde_core/src/ser/fmt.rs

@@ -1,9 +1,5 @@
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 use crate::ser::{Error, Impossible, Serialize, Serializer};
 
 impl Error for fmt::Error {

serde_core/src/ser/impls.rs

@@ -1,11 +1,5 @@
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-// Even when "std" feature is enabled (due to Cargo feature unification),
-// the prelude may not be injected on wasm32v1-none target
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 use crate::ser::{Error, Serialize, SerializeTuple, Serializer};
 
 ////////////////////////////////////////////////////////////////////////////////

serde_core/src/ser/impossible.rs

@@ -2,10 +2,6 @@
 
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 use crate::ser::{
     self, Serialize, SerializeMap, SerializeSeq, SerializeStruct, SerializeStructVariant,
     SerializeTuple, SerializeTupleStruct, SerializeTupleVariant,

serde_core/src/ser/mod.rs

@@ -109,10 +109,6 @@
 
 use crate::lib::*;
 
-// Explicit prelude import for wasm32v1-none and other no_std targets
-#[allow(unused_imports)]
-use ::core::prelude::rust_2021::*;
-
 mod fmt;
 mod impls;
 mod impossible;