ci: try removing --impure

Signed-off-by: strawberry <strawberry@puppygock.gay>

.github/workflows/documentation.yml

@@ -101,7 +101,7 @@ jobs:
       - name: Prepare build environment
         run: |
             echo 'source $HOME/.nix-profile/share/nix-direnv/direnvrc' > "$HOME/.direnvrc"
-            nix profile install --impure --inputs-from . nixpkgs#direnv nixpkgs#nix-direnv
+            nix profile install --inputs-from . nixpkgs#direnv nixpkgs#nix-direnv
             direnv allow
             nix develop --command true