only explicitly clone the scripts repo if a ref is given

.github/workflows/build-linux.yml

@@ -67,15 +67,12 @@ jobs:
           ref: ${{ inputs.dfhack_ref }}
           submodules: true
           fetch-depth: ${{ !inputs.platform-files && 1 || 0 }}
-      - name: Get scripts submodule ref
-        if: '!inputs.scripts_ref'
-        id: scriptssubmoduleref
-        run: echo ref=$(git submodule | fgrep scripts | cut -c2-41) >> $GITHUB_OUTPUT
       - name: Clone scripts
+        if: inputs.scripts_ref
         uses: actions/checkout@v3
         with:
           repository: 'DFHack/scripts'
-          ref: ${{ inputs.scripts_ref || steps.scriptssubmoduleref.outputs.ref }}
+          ref: ${{ inputs.scripts_ref }}
           path: scripts
       - name: Fetch ccache
         if: inputs.platform-files