batches: feature detection fails in src batch validate

Created by: LawnGnome

I'm not sure of the root cause yet, but any spec feature that relies on Sourcegraph feature detection currently fails. For example, with a batch spec using workspaces:

$ src batch validate -f ../scratch/new-campaigns/workspaces.batch.yaml 
parsing batch spec: 1 error occurred:
	* batch spec includes workspaces, which is not supported in this Sourcegraph version

But actually executing the spec is fine:

$ src batch preview -f ../scratch/new-campaigns/workspaces.batch.yaml 
✅ Parsing batch spec
✅ Resolving namespace
✅ Preparing container images  ███████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████
✅ Set workspace type
✅ Resolved 1 repositories
✅ Found 1 workspaces with steps to execute
✅ Found 0 cached changeset specs; 1 task needs to be executed
✅ Executing... (1/1, 0 errored)  ████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████
✅ Sending changeset spec  ███████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████████
✅ Creating batch spec on Sourcegraph

✅ To preview or apply the batch spec, go to: