github-cachix: added iohk cache

.github/workflows/posix.yml

@@ -7,18 +7,17 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v2
-      - uses: cachix/install-nix-action@v10
+      - uses: cachix/install-nix-action@v12
+        with:
+          extra_nix_config: |
+            substituters = https://cache.nixos.org https://hydra.iohk.io
+            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
       - name: "cachix"
-        uses: cachix/cachix-action@v6
+        uses: cachix/cachix-action@v8
         with:
           name: "free-algebras"
           signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
 
-      - name: "nix"
-        run: |
-            echo 'substituters = https://hydra.iohk.io/' | sudo tee -a /etc/nix/nix.conf
-            echo 'trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=' | sudo tee -a /etc/nix/nix.conf
-
       - name: "cachix iohk"
         run: cachix use iohk
 

cabal.project

@@ -1,3 +1,3 @@
-index-state: 2020-10-10T00:00:00Z
+index-state: 2020-03-11T00:00:00Z
 packages: free-category.cabal
 	  examples/examples.cabal