Bump externals/sgdk from 6a88e15 to d86e86c (#708)

Bumps [externals/sgdk](https://github.com/Stephane-D/SGDK) from `6a88e15` to `d86e86c`.
- [Release notes](https://github.com/Stephane-D/SGDK/releases)
- [Commits](Stephane-D/SGDK@6a88e15...d86e86c)

---
updated-dependencies:
- dependency-name: externals/sgdk
  dependency-version: d86e86c28958af78aebefb6068ab43c82879670a
  dependency-type: direct:production
...

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