Specify miri toolchain for CI example
In particular current example doesn't work if you have a rust-toolchain file in the project.
-cc9610bf5af1d5c54968db0dd899595ca12307a0
+a50d72158e08e02cfc051b863017bdbd2c45b637
Caught panic message (String): Hello from panic: 1
thread 'main' panicked at 'Hello from panic: 2', $DIR/catch_panic.rs:LL:26
Caught panic message (String): Hello from panic: 2
-thread 'main' panicked at 'Box<Any>', $DIR/catch_panic.rs:LL:27
+thread 'main' panicked at 'Box<dyn Any>', $DIR/catch_panic.rs:LL:27
Failed to get caught panic message.
thread 'main' panicked at 'Hello from panic: core', $DIR/catch_panic.rs:LL:27
Caught panic message (&str): Hello from panic: core