chore: changed errors3 mode from test to compile

info.toml

@@ -470,7 +470,7 @@ and give it a try!"""
 [[exercises]]
 name = "errors3"
 path = "exercises/error_handling/errors3.rs"
-mode = "test"
+mode = "compile"
 hint = """
 If other functions can return a `Result`, why shouldn't `main`?"""