Simplify release process

[skjnldsv]

Releasing a new version

• Pull the latest changes from master or stableX;
• Checkout a new branch with the tag name (e.g v4.0.1): git checkout -b v<version>;
• Run npm version patch --no-git-tag-version (npm version minor --no-git-tag-version if minor). This will return a new version name, make sure it matches what you expect;
• Commit, push and create PR;
• Add the change log content from the 'Changelog' action on Github to CHANGELOG.md;
• Commit and push;
• Get your PR reviewed and merged;
• Create a release on github with the version as tag (e.g v4.0.1) and add the changelog content as description (https://github.com/nextcloud/nextcloud-vue/releases);