Fix compilation under rust 1.89

Rust 1.89 produces the following output:

```
error: unicode codepoint changing visible direction of text present in literal
...
warning: allow(text_direction_codepoint_in_literal) is ignored unless specified at crate level
 --> rslib/i18n/src/generated.rs:7:10
  |
7 | #![allow(text_direction_codepoint_in_literal)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```

This change fixes it.

This ensures that some third-party crate that pulls in this code as
library code (and thus isn't subject to the rust-toolchain file in this
repo) doesn't hit this compilation error.

rslib/i18n/src/generated.rs

@@ -4,6 +4,5 @@
 // Include auto-generated content
 
 #![allow(clippy::all)]
-#![allow(text_direction_codepoint_in_literal)]
 
 include!(concat!(env!("OUT_DIR"), "/strings.rs"));

rslib/i18n/src/lib.rs

@@ -1,6 +1,7 @@
 // Copyright: Ankitects Pty Ltd and contributors
 // License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
+#![allow(text_direction_codepoint_in_literal)]
 mod generated;
 
 use std::borrow::Cow;