ci: fix incorrect cache key (AGAIN BRO)

Author: CompeyDev

.github/workflows/ci.yml

@@ -82,7 +82,7 @@ jobs:
       - name: Restore and cache Nix store
         uses: nix-community/cache-nix-action@v6
         with:
-          primary-key: nix-${{ runner.os }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
+          primary-key: nix-${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('**/*.nix', '**/flake.lock') }}
           restore-prefixes-first-match: nix-${{ runner.os }}-${{ runner.arch }}-
           gc-max-store-size-linux: 5368709000 
           purge: true