chore(ci): correctly compute the `DIST_TAG` environment variable
chore(ci): correctly compute the `DIST_TAG` environment variable

Previously, the `DIST_TAG` environment variable was failing to be
computed correctly, because it was using the non-existent `jq` tool. In
the past (when running on TravisCI), `jq` used to be available, but it
is not on the currently used CircleCI docker image, resulting in the
following error:

```sh
./.circleci/env.sh: line 59: jq: command not found
DIST_TAG=
```

You can see an example failure in the "Set up environment" step logs in
https://app.circleci.com/pipelines/github/angular/angular.js/
166/workflows/34c692ec-18d4-4422-a1cf-108a91219fa5/jobs/1742

This commit fixes it by using `node` (which _is_ available on the docker
image) to compute `$DIST_TAG`.

mosoft521/angular.js,ze-pequeno/angular.js,ze-pequeno/angular.js,mgol/angular.js,mgol/angular.js,eistrati/angular.js,angular/angular.js,eistrati/angular.js,eistrati/angular.js,ze-pequeno/angular.js,mosoft521/angular.js,mosoft521/angular.js,gkalpak/angular.js,mgol/angular.js,angular/angular.js,gkalpak/angular.js,angular/angular.js,gkalpak/angular.js,mgol/angular.js,angular/angular.js,mosoft521/angular.js,eistrati/angular.js,ze-pequeno/angular.js,gkalpak/angular.js