chore: add shell

Author: vmx

.github/actions/proof-params-download/action.yml

@@ -43,10 +43,12 @@ runs:
         run-id: ${{ fromJson(steps.latest-proof-params.outputs.data).workflow_runs[0].id }}
         github-token: ${{ inputs.github-token }}
     - name: Obtain Filecoin IPP parameter file
+      shell: bash
       # paramfetch is using `ipget` which currently always times out on
       # CI, hence get this file via HTTP instead.
       #cargo run --release --bin paramfetch -- -a -j srs-inner-product.json
       # `--insecure` is needed due to an outdated base systems.
       run: 'curl --insecure https://proofs.filecoin.io/v28-fil-inner-product-v1.srs --output /var/tmp/filecoin-proof-parameters/v28-fil-inner-product-v1.srs'
     - name: List parameter files
+      shell: bash
       run: ls -al /var/tmp/filecoin-proof-parameters/