add iog keys

Author: georgefst

.github/workflows/haskell.yml

@@ -15,6 +15,9 @@ jobs:
       - uses: cachix/install-nix-action@v30
         with:
           github_access_token: ${{ secrets.GITHUB_TOKEN }}
+          extra_nix_config: |
+            extra-substituters = https://cache.iog.io
+            extra-trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
       - uses: cachix/cachix-action@v15
         with:
           name: georgefst