provide missing shell param to github action

Author: nkanaev

.github/actions/prepare/action.yml

@@ -14,8 +14,10 @@ runs:
   steps:
     - name: compile
       run: ${{ inputs.cmd }}
+      shell: bash
     - name: archive
       run: tar -cvf ${{ out }}.tar ${{ out }}
+      shell: bash
     - name: upload
       uses: actions/upload-artifact@v4
       with: