ci: gba crate is broken due to recent nightly bug

rust-lang/rust#127853 (comment)

```
  error[E0736]: attribute incompatible with `#[naked]`
     --> /home/runner/.cargo/registry/src/index.crates.io-6f17d22bba15001f/gba-0.11.6/src/asm_runtime.rs:164:1
      |
  164 | /// Returns 0 in `r0`, while placing the `numerator` into `r1`.
      | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the `` attribute is incompatible with `#[naked]`
  ...
  172 | #[naked]
      | -------- function marked with `#[naked]` here
```

tools/build.sh

@@ -346,7 +346,8 @@ build() {
                 local test_dir=''
                 # NB: sync with tools/no-std.sh
                 case "${target}" in
-                    armv4t* | thumbv4t*) test_dir=tests/gba ;;
+                    # TODO: https://github.com/rust-lang/rust/pull/127853#issuecomment-2257323333
+                    # armv4t* | thumbv4t*) test_dir=tests/gba ;;
                     arm* | thumb* | riscv*) test_dir=tests/no-std-qemu ;;
                     avr-unknown-gnu-atmega2560) test_dir=tests/avr ;; # tests/avr is for atmega2560 not atmega328
                 esac