Auto format let-else block (#10214)

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rustfmt 1.6.0 has added support for formatting [let-else
statements](https://doc.rust-lang.org/rust-by-example/flow_control/let_else.html)

See https://github.com/rust-lang/rustfmt/blob/master/CHANGELOG.md#added

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crates/nu-cmd-lang/src/core_commands/match_.rs

@@ -53,8 +53,9 @@ impl Command for Match {
                     }
 
                     let guard_matches = if let Some(guard) = &match_.0.guard {
-                        let Value::Bool { val, .. } = eval_expression(engine_state, stack, guard)? else {
-                            return Err(ShellError::MatchGuardNotBool { span: guard.span});
+                        let Value::Bool { val, .. } = eval_expression(engine_state, stack, guard)?
+                        else {
+                            return Err(ShellError::MatchGuardNotBool { span: guard.span });
                         };
 
                         val

crates/nu-cmd-lang/src/core_commands/use_.rs

@@ -52,7 +52,8 @@ This command is a parser keyword. For details, check:
         let Some(Expression {
             expr: Expr::ImportPattern(import_pattern),
             ..
-        }) = call.get_parser_info("import_pattern") else {
+        }) = call.get_parser_info("import_pattern")
+        else {
             return Err(ShellError::GenericError(
                 "Unexpected import".into(),
                 "import pattern not supported".into(),