Update rectangle-pack requirement from 0.3 to 0.4 (#2086)

Updates the requirements on [rectangle-pack](https://github.com/chinedufn/rectangle-pack) to permit the latest version.
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Author: dependabot[bot]

crates/bevy_sprite/Cargo.toml

@@ -27,7 +27,7 @@ bevy_utils = { path = "../bevy_utils", version = "0.5.0" }
 bevy_window = { path = "../bevy_window", version = "0.5.0" }
 
 # other
-rectangle-pack = "0.3"
+rectangle-pack = "0.4"
 thiserror = "1.0"
 guillotiere = "0.6.0"
 serde = { version = "1", features = ["derive"] }