Revert CI changes

Author: sestrella

.github/workflows/ci.yaml

@@ -16,9 +16,7 @@ jobs:
         name: pre-commit-hooks
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
     - run: rm -rf /opt&
-    - run: nix-build --keep-going --impure
-      env:
-        NIXPKGS_ALLOW_UNFREE: 1
+    - run: nix-build --keep-going
   tests-flakes:
     strategy:
       matrix:
@@ -32,7 +30,5 @@ jobs:
         name: pre-commit-hooks
         signingKey: '${{ secrets.CACHIX_SIGNING_KEY }}'
     - run: rm -rf /opt&
-    - run: nix flake check -L --show-trace --impure
-      env:
-        NIXPKGS_ALLOW_UNFREE: 1
+    - run: nix flake check -L --show-trace
     - run: nix eval .#lib.x86_64-linux.run --show-trace