v1/web/core/assets/vendor/modernizr

For some reason the link in the core file https://modernizr.com/download/?-details-inputtypes-addtest-mq-prefixed-prefixes-setclasses-teststyles always produces a 3.6.0 version when using the Build option.

Browse to the same URL and use the Command Line Config option to Download the config JSON file modernizr-config.json.

Following the instructions here https://modernizr.com/docs

sudo npm install -g npm
npm install -g modernizr
modernizr -c modernizr-config.json // This is the file downloaded from http://modernizr.com/download

This produces a modernizr.js file that should be renamed to modernizr.min.js and copied to core/assets/vendor/modernizr/modernizr.min.js.

Please also remember to update the version number of Modernizer in core/core.libraries.yml.