fs: remove unnecessary trait and lifetime bounds (#1655)

tokio-fs/src/read_dir.rs

@@ -19,7 +19,7 @@ use std::task::Poll;
 /// This is an async version of [`std::fs::read_dir`](std::fs::read_dir)
 pub async fn read_dir<P>(path: P) -> io::Result<ReadDir>
 where
-    P: AsRef<Path> + Send + 'static,
+    P: AsRef<Path>,
 {
     let path = path.as_ref().to_owned();
     let std = asyncify(|| std::fs::read_dir(path)).await?;

tokio-fs/src/symlink_metadata.rs

@@ -11,7 +11,7 @@ use std::path::Path;
 /// [std]: https://doc.rust-lang.org/std/fs/fn.symlink_metadata.html
 pub async fn symlink_metadata<P>(path: P) -> io::Result<Metadata>
 where
-    P: AsRef<Path> + Send + 'static,
+    P: AsRef<Path>,
 {
     let path = path.as_ref().to_owned();
     asyncify(|| std::fs::symlink_metadata(path)).await

tokio-fs/src/write.rs

@@ -19,7 +19,7 @@ use std::{io, path::Path};
 /// ```
 pub async fn write<P, C: AsRef<[u8]> + Unpin>(path: P, contents: C) -> io::Result<()>
 where
-    P: AsRef<Path> + Send + Unpin + 'static,
+    P: AsRef<Path>,
 {
     let path = path.as_ref().to_owned();
     let contents = contents.as_ref().to_owned();