fix(tests1): Change test command
Closes
// tests1.rs
// Tests are important to ensure that your code does what you think it should do.
// Tests can be run on this file with the following command:
-// rustlings run --test exercises/tests/tests1.rs
+// rustlings run exercises/tests/tests1.rs
// This test has a problem with it -- make the test compile! Make the test
// pass! Make the test fail! Execute `rustlings hint tests1` for hints :)
