Gitpod does not build docker-protoc

This link https://gitpod.io/#https://github.com/namely/docker-protoc opens the repo in Gitpod and the make command fails at step 67/101
```
Step 67/101 : RUN npm config set unsafe-perm true
 ---> Running in e9943670f51a
/bin/sh: 1: npm: not found
The command '/bin/sh -c npm config set unsafe-perm true' returned a non-zero code: 127
```