niv candid: update 331217ba -> e212e096

## Changelog for candid:
Branch: master
Commits: [dfinity/candid@331217ba...e212e096](dfinity/candid@331217b...e212e09)

* [`a71eb20a`](dfinity/candid@a71eb20) limit size of vec null/reserved ([dfinity/candid⁠#434](https://togithub.com/dfinity/candid/issues/434))
* [`de8b57a0`](dfinity/candid@de8b57a) [Rust] Add composite_query ([dfinity/candid⁠#435](https://togithub.com/dfinity/candid/issues/435))
* [`e212e096`](dfinity/candid@e212e09) add play.motoko.org to Candid UI ([dfinity/candid⁠#437](https://togithub.com/dfinity/candid/issues/437))

nix/sources.json

@@ -6,10 +6,10 @@
         "homepage": "",
         "owner": "dfinity",
         "repo": "candid",
-        "rev": "331217bae379cbebfa531a140f2186c99fae1425",
-        "sha256": "095w2a4lxy2gd7vfjxn7jszm4x3srw8xlxb1zzd096y6h047rxlj",
+        "rev": "e212e096cb726548c6d6edba1189375dc5ad364e",
+        "sha256": "0wixm6xiwbdb6bq783zniaygh161gzsspsrw60izs1r9xfcx2h0r",
         "type": "tarball",
-        "url": "https://github.com/dfinity/candid/archive/331217bae379cbebfa531a140f2186c99fae1425.tar.gz",
+        "url": "https://github.com/dfinity/candid/archive/e212e096cb726548c6d6edba1189375dc5ad364e.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "esm": {