Add substituters to CI workflows

Author: ch1bo

.github/workflows/ci.yaml

@@ -27,6 +27,8 @@ jobs:
         extra_nix_config: |
           accept-flake-config = true
           log-lines = 1000
+          trusted-public-keys = iohk.cachix.org-1:DpRUyj7h7V830dp/i6Nti+NEO2/nhblbov/8MW7Rqoo= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+          substituters = https://iohk.cachix.org https://cache.iog.io https://cache.nixos.org/
 
     - name: Github cache ~/.cabal/packages, ~/.cabal/store and dist-newstyle
       uses: actions/cache@v4

.github/workflows/release.yaml

@@ -23,6 +23,8 @@ jobs:
         extra_nix_config: |
           accept-flake-config = true
           log-lines = 1000
+          trusted-public-keys = iohk.cachix.org-1:DpRUyj7h7V830dp/i6Nti+NEO2/nhblbov/8MW7Rqoo= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+          substituters = https://iohk.cachix.org https://cache.iog.io https://cache.nixos.org/
 
     - name: Github cache ~/.cabal/packages, ~/.cabal/store and dist-newstyle
       uses: actions/cache@v4