If you use optionalDependencies instead, npm install works on Linux w…

…ithout errors about dmg-license cannot be installed.

I get this error without this change:

```
npm WARN deprecated puppeteer@2.1.1: < 19.4.0 is no longer supported
npm WARN deprecated @braintree/sanitize-url@3.1.0: Potential XSS vulnerability patched in v6.0.0.
npm WARN deprecated w3c-hr-time@1.0.2: Use your platform's native performance.now() and performance.timeOrigin.
npm ERR! code EBADPLATFORM
npm ERR! notsup Unsupported platform for dmg-license@1.0.11: wanted {"os":"darwin","arch":"any"} (current: {"os":"linux","arch":"x64"})
npm ERR! notsup Valid OS:    darwin
npm ERR! notsup Valid Arch:  any
npm ERR! notsup Actual OS:   linux
npm ERR! notsup Actual Arch: x64

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/user/.npm/_logs/2023-04-04T23_28_28_809Z-debug.log
```

Changing to an optionalDependency allowed me to proceed without errors.

package.json

@@ -41,7 +41,7 @@
   "repository": "https://github.com/electron-userland/electron-builder",
   "///": "All dependencies for all packages (hoisted)",
   "////": "All typings are added into root `package.json` to avoid duplication errors in the IDE compiler (several `node.d.ts` files).",
-  "dependencies": {
+  "optionalDependencies": {
     "dmg-license": "1.0.11"
   },
   "devDependencies": {