Add SSH deploy key to TagBot workflow

Author: joshday

.github/workflows/TagBot.yml

@@ -16,4 +16,5 @@ jobs:
       - uses: JuliaRegistries/TagBot@v1
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
-          ssh: ${{ secrets.DOCUMENTER_KEY }}
+          ssh: ${{ secrets.TAGBOT_SSH }}
+          ssh: ${{ secrets.DOCUMENTER_KEY }}