note: I upgraded npm 2 months ago to these will be minor or no upgrades.
Determine what npm version you are currently at. First cd change directory into project directory. In my case it is Sites/11ty-ahs
% cd Sites/11ty-ahs
% npm list
npm list
├── @11ty/eleventy-navigation@0.3.2
├── @11ty/eleventy-plugin-webc@0.9.4
├── @11ty/eleventy-upgrade-help@3.0.1
├── @11ty/eleventy@3.0.0
├── dayjs@1.11.13
└── npm@11.0.0
upgrade to the lastest version of npm and dayjs
npm install npm@latest
npm upgrade dayjs
npm list
├── @11ty/eleventy-navigation@0.3.2
├── @11ty/eleventy-plugin-webc@0.9.4
├── @11ty/eleventy-upgrade-help@3.0.1
├── @11ty/eleventy@3.0.0
├── dayjs@1.11.13
└── npm@11.1.0
npm is now at 11.1.0 and dayjs did not change