attempting as an ssh-key instead of a token

.github/workflows/steam.yml

@@ -32,13 +32,12 @@ jobs:
           submodules: true
           fetch-depth: 0
           ref: ${{ github.event.inputs.commit_hash }}
-          persist-credentials: false
       - name: Get 3rd party SDKs
         uses: actions/checkout@v3
         with:
           repository: DFHack/3rdparty
           ref: main
-          token: ${{ secrets.DFHACK_3RDPARTY_TOKEN }}
+          ssh-key: ${{ secrets.DFHACK_3RDPARTY_TOKEN }}
           path: depends
       - name: Fetch ccache
         uses: actions/cache@v3