If I follow the instructions in the readme and specify an env var like this in .graphclientrc.yml: ``` sources: - name: farther handler: graphql: endpoint: https://api.studio.thegraph.com/query/{env.SUBGRAPH}/version/latest ``` and then start the process with the following script: `SUBGRAPH=<subgraph-id> graphclient build` ...the variable doesn't get injected. Does anyone know why?