macros: add missing local flavor to tokio::main error message (#7597)

Author: martin-g

tests-build/tests/fail/macros_invalid_input.stderr

@@ -40,7 +40,7 @@ error: Failed to parse value of `flavor` as string.
 23 | #[tokio::test(flavor = 123)]
    |                        ^^^
 
-error: No such runtime flavor `foo`. The runtime flavors are `current_thread` and `multi_thread`.
+error: No such runtime flavor `foo`. The runtime flavors are `current_thread`, `local`, and `multi_thread`.
   --> tests/fail/macros_invalid_input.rs:26:24
    |
 26 | #[tokio::test(flavor = "foo")]

tokio-macros/src/entry.rs

@@ -22,7 +22,7 @@ impl RuntimeFlavor {
             "single_thread" => Err("The single threaded runtime flavor is called `current_thread`.".to_string()),
             "basic_scheduler" => Err("The `basic_scheduler` runtime flavor has been renamed to `current_thread`.".to_string()),
             "threaded_scheduler" => Err("The `threaded_scheduler` runtime flavor has been renamed to `multi_thread`.".to_string()),
-            _ => Err(format!("No such runtime flavor `{s}`. The runtime flavors are `current_thread` and `multi_thread`.")),
+            _ => Err(format!("No such runtime flavor `{s}`. The runtime flavors are `current_thread`, `local`, and `multi_thread`.")),
         }
     }
 }