mcaptcha: meta.url should be meta.homepage

### Instructions Follow the [contribution guide](https://github.com/ngi-nix/ngipkgs/blob/main/CONTRIBUTING.md) and add the ngi team in `meta.teams` if it's not already there: ```nix meta.teams = with lib.teams; [ ngi ]; ``` ### Problem `pkgs/by-name/mcaptcha/package.nix` uses `url` inside the `meta` block: ```nix meta = { url = "https://mcaptcha.org/"; ... }; ``` `url` is not a recognised Nixpkgs meta attribute. The correct key is `homepage`. With `meta.url`, the project homepage is invisible to `nix search`, the overview page, and audit tooling. ### Fix Rename the key: ```nix meta = { homepage = "https://mcaptcha.org/"; ... }; ``` While touching this file also add `meta.maintainers` and `meta.teams = with lib.teams; [ ngi ]` if they are missing.