update nix in CI

Author: juliankuners

.github/workflows/test-pr.yml

@@ -221,7 +221,7 @@ jobs:
         if: ${{ matrix.runner != 'MacM1' }}
         uses: cachix/[email protected]
         with:
-          install_url: https://releases.nixos.org/nix/nix-2.24.12/install
+          install_url: https://releases.nixos.org/nix/nix-31.2.0/install
           extra_nix_config: |
             substituters = http://cache.nixos.org https://cache.iog.io
             trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=

.github/workflows/update-version.yml

@@ -31,7 +31,7 @@ jobs:
       - name: 'Install Nix'
         uses: cachix/[email protected]
         with:
-          install_url: https://releases.nixos.org/nix/nix-2.24.12/install
+          install_url: https://releases.nixos.org/nix/nix-31.2.0/install
           extra_nix_config: |
             substituters = http://cache.nixos.org https://cache.iog.io
             trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=