ci: force AMD64 remote execution executors

When running on `arm64` executors the following error occurs:

```
../ape~1.0.0-beta.4/ape/toolchain/ape/ape-arm64-linux/ape-arm64-linux: 1: ../ape~1.0.0-beta.4/ape/toolchain/ape/ape-arm64-linux/ape-arm64-linux: Syntax error: "(" unexpected
```

This may be due to the executors having a custom `binfmt_misc` setup.

It needs more debugging but we can force AMD64 executors for now.