ci: fix permissions in ci-docker workflow (#370)

Signed-off-by: Aurora Gaffney <[email protected]>

Author: agaffney

.github/workflows/ci-docker.yml

@@ -9,7 +9,7 @@ env:
   GHCR_IMAGE_NAME: ghcr.io/blinklabs-io/cardano-up
 
 permissions:
-  content: read
+  contents: read
 
 jobs:
   docker: