fix: install turbo as optional dependency (#629)

### Description of the Change

Closes #617

### How to test the Change
Run npm install from machines with different architectures and
platforms:
- Darwin x64
- Darwin arm64
- Linux x64
- Linux arm64
- Windows x64
- Windows arm64


### Checklist:
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that apply. -->
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- [x] I agree to follow this project's [**Code of
Conduct**](https://github.com/10up/.github/blob/trunk/CODE_OF_CONDUCT.md).
- [ ] I have updated the documentation accordingly.
- [ ] I have added tests to cover my change.
- [ ] All new and existing tests pass.

package.json

@@ -61,5 +61,13 @@
   },
   "dependencies": {
     "express": "^4.18.1"
+  },
+  "optionalDependencies": {
+    "turbo-darwin-64": "^1.9.3",
+    "turbo-darwin-arm64": "^1.9.3",
+    "turbo-linux-64": "^1.9.3",
+    "turbo-linux-arm64": "^1.9.3",
+    "turbo-windows-64": "^1.9.3",
+    "turbo-windows-arm64": "^1.9.3"
   }
 }