fix: gh-pages workflow

Signed-off-by: Brian McGee <brian@bmcgee.ie>

.github/workflows/gh-pages.yml

@@ -33,7 +33,7 @@ jobs:
             - name: Deploy main
               if: ${{ github.ref_name == 'main' }}
               run: |
-                  nix develop --command bash -c "mike deploy -p main"
+                  nix develop .#docs --command bash -c "mike deploy -p main"
             - name: Deploy version
               if: startsWith(github.ref, 'refs/tags/v')
               run: |