• I have read the contribution documentation for this project.
• I agree to follow the code of conduct that this project follows, as appropriate.
• The changes are appropriately documented (if applicable).
• The changes have sufficient test coverage (if applicable).
• The testsuite passes successfully on my local machine (if applicable).

Summarize your changes:
This PR ensures that the most recent compatible version of @electron-forge/plugin-webpack will be installed by create-electron-app. While the package.json might still show an older version when using create-electron-app (as outlined in #3019 (comment)), the version yarn / npm will actually install is the most recent.