chore: add ssh key for signin commit (#2340)

Author: jremy42

.github/workflows/deploy-package.yml

@@ -15,6 +15,19 @@ jobs:
           fetch-depth: '0'
           persist-credentials: false
       - run: git fetch --depth=1 origin +refs/tags/*:refs/tags/*
+
+      - name: Setup SSH signing
+        run: |
+          mkdir -p ~/.ssh
+          echo "${{ secrets.SSH_SIGNING_PRIVATE_KEY }}" > ~/.ssh/signing_key
+          chmod 600 ~/.ssh/signing_key
+          echo "${{ secrets.SSH_SIGNING_PUBLIC_KEY }}" > ~/.ssh/signing_key.pub
+          chmod 644 ~/.ssh/signing_key.pub
+          git config --global gpg.format ssh
+          git config --global user.signingkey ~/.ssh/signing_key.pub
+          git config --global commit.gpgsign true
+          git config --global tag.gpgsign true
+
       - name: Git Identity
         run: |
           git config --global user.name 'scaleway-bot'