fix ci

.github/workflows/ci.yaml

@@ -14,16 +14,16 @@ jobs:
 
       - name: Populate Nix store
         run:
-          nix-shell --run 'true'
+          nix-shell --pure --run 'true'
 
       - name: Type-check with lua-language-server
         run:
-          nix-shell --run 'make lint'
+          nix-shell --pure --run 'make lint'
 
       - name: Check formatting with stylua
         run:
-          nix-shell --run 'make fmt-check'
+          nix-shell --pure --run 'make fmt-check'
 
       - name: Run busted tests
         run:
-          nix-shell --run 'make test'
+          nix-shell --pure --run 'make test'