Add secret for github action (GITHUB_TOKEN)

Author: Aleksandr Penskoi

.github/workflows/integrate.yaml

@@ -62,6 +62,7 @@ jobs:
             trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= iohk.cachix.org-1:DpRUyj7h7V830dp/i6Nti+NEO2/nhblbov/8MW7Rqoo= cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
             substituters = https://hydra.iohk.io https://iohk.cachix.org https://cache.nixos.org/
             extra-experimental-features = nix-command flakes
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
       - uses: cachix/cachix-action@v10
         with:
           name: mlabs