Change filename to blind_alerter.go (quii#554)

Fix the casing on BlindAlerter.go to be consistent.

When comparing with https://github.com/quii/learn-go-with-tests/tree/main/time/v1 the filename should be snake case instead.

Author: lucasmelin

time.md

@@ -375,7 +375,7 @@ Try running the app and it won't compile, complaining about not enough args to `
 
 Let's create an implementation of `BlindAlerter` that we can use in our application.
 
-Create `BlindAlerter.go` and move our `BlindAlerter` interface and add the new things below
+Create `blind_alerter.go` and move our `BlindAlerter` interface and add the new things below
 
 ```go
 package poker