bump rust toolchain to 1.68.2 (#9346)

# Description

In keeping with our tradition of staying 2 versions behind the latest
rust compiler version, this PR bump the toolchain to 1.68.2.

# User-Facing Changes
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# Tests + Formatting
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crates/nu-command/src/filesystem/ls.rs

@@ -835,16 +835,14 @@ mod windows_helper {
                 &mut find_data,
             ) {
                 Ok(_) => Ok(find_data),
-                Err(e) => {
+                Err(e) => Err(ShellError::ReadingFile(
-                    return Err(ShellError::ReadingFile(
                     format!(
                         "Could not read metadata for '{}':\n  '{}'",
                         filename.to_string_lossy(),
                         e
                     ),
                     span,
-                    ));
+                )),
-                }
             }
         }
     }

rust-toolchain.toml

@@ -16,5 +16,5 @@ profile = "default"
 # use in nushell, we may opt to use the bleeding edge stable version of rust.
 # I believe rust is on a 6 week release cycle and nushell is on a 3 week release cycle.
 # So, every two nushell releases, this version number should be bumped by one.
-channel = "1.67.1"
+channel = "1.68.2"