Allow release from yarn run

Running `yarn run release` causes issues as it can't communicate with
the proper npm registry. This happens because yarn overrides the
`npm_config_registry` variable, on which the publishing depends.

In this commit I revert the value to its default, allowing the release
script to be run either with `npm run release` or `yarn run release`.

scripts/release

@@ -2,6 +2,10 @@
 
 set -e # exit when error
 
+# When running through yarn, this variable is changed, preventing the publishing
+# to actually work. We revert it to its default value.
+export npm_config_registry='https://registry.npmjs.org/'
+
 if ! npm owner ls | grep -q "$(npm whoami)"
 then
   printf "Release: Not an owner of the npm repo, ask for it"