Update base64 requirement from 0.12.3 to 0.13.0

Updates the requirements on [base64](https://github.com/marshallpierce/rust-base64) to permit the latest version.
- [Release notes](https://github.com/marshallpierce/rust-base64/releases)
- [Changelog](https://github.com/marshallpierce/rust-base64/blob/master/RELEASE-NOTES.md)
- [Commits](marshallpierce/rust-base64@v0.12.3...v0.13.0)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

crates/bevy_gltf/Cargo.toml

@@ -29,4 +29,4 @@ gltf = { version = "0.15.2", default-features = false, features = ["utils"] }
 image = { version = "0.23.12", default-features = false }
 thiserror = "1.0"
 anyhow = "1.0"
-base64 = "0.12.3"
+base64 = "0.13.0"