ci-builder: add changeset

The next time that a release is triggered, build and publish
the `ci-builder` docker image. This will cause it to be used
in CI for builds, meaning that we will need to update our
foundry versions for local development.

This can be done with the following command:

```bash
foundryup -C edf15abd648bb96e2bcee342c1d72ec7d1066cd1
```

.changeset/fifty-schools-think.md

+---
+'@eth-optimism/ci-builder': patch
+---
+
+Bump foundry to edf15abd648bb96e2bcee342c1d72ec7d1066cd1