Installing from GitHub source will not include `lib`, `dist` and `esm` folders

[RinkeHoekstra]

When installing rdflib from latest source, e.g. through GitHub, the npm install script does not build the package properly and does not create the lib, dist and esm folders.

[angelo-v]

npm install is not enough, you need to run npm run build, npm run build:esm and/or npm run build:browser to create those directories