Also bump cardano-node in niv

Matches revision in snapshot.yaml.

I can fix it later so that the cardano-node rev is defined in only one
place, in the stack snapshot.

nix/sources.json

@@ -1,14 +1,14 @@
 {
     "cardano-node": {
-        "branch": "1.14.2",
+        "branch": "release/1.14.x",
         "description": null,
         "homepage": null,
         "owner": "input-output-hk",
         "repo": "cardano-node",
-        "rev": "924a6f7d8c2bdb1bf525be8b0d5626e440697b01",
-        "sha256": "0bi1vwmb1w6wc2szpr8v1nbsci9y36lnjr4v5pli1wvll1hhpw3c",
+        "rev": "a2161bac700fac55d2400b37f9935ed8ea527550",
+        "sha256": "1yjfh82ikp9g5prxdcfgg0ni8lgy1k45p8hxk8dc736qgbc495pm",
         "type": "tarball",
-        "url": "https://github.com/input-output-hk/cardano-node/archive/924a6f7d8c2bdb1bf525be8b0d5626e440697b01.tar.gz",
+        "url": "https://github.com/input-output-hk/cardano-node/archive/a2161bac700fac55d2400b37f9935ed8ea527550.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "haskell.nix": {