fix(sign): Remove unused registry extraction

sign/action.yml

@@ -5,26 +5,22 @@ inputs:
   containers:
     description: 'Names of target containers to sign'
     required: true
+  registry:
+    description: 'Registry where the container resides'
+    default: 'ghcr.io/ublue-os'
+    required: true
   registry-token:
     description: 'Password for container registry'
     required: true
   signing-secret:
     description: 'Private key used to sign target container.'
     required: true
-  registry:
-    description: 'Registry where the container resides'
-    default: 'ghcr.io/ublue-os'
-    required: true
   tags:
     description: 'Tags used by target container'
     required: true
 runs:
   using: "composite"
   steps:
-    - name: Extract registry from container path
-      shell: bash
-      run: echo "REGISTRY=$(cut -d '/' -f 1 <<< ${{ inputs.container }})" >> $GITHUB_ENV
-
     - name: Login to Container Registry
       uses: docker/login-action@v3
       with: