niv motoko-base: update 822e35d4 -> f6efca43 (#3648)

## Changelog for motoko-base:
Branch: next-moc
Commits: [dfinity/motoko-base@822e35d4...f6efca43](dfinity/motoko-base@822e35d...f6efca4)

* [`88da21cd`](dfinity/motoko-base@88da21c) Add formatter configuration file
* [`ce163081`](dfinity/motoko-base@ce16308) Reformat all

Author: dfinity-bot

nix/sources.json

@@ -64,10 +64,10 @@
         "homepage": null,
         "owner": "dfinity",
         "repo": "motoko-base",
-        "rev": "822e35d4c167b34808301e00655f67a516053b44",
-        "sha256": "1ik99d9fls4ad74a3r24j9nmrsqznxw5ff9b5pz1lwm598qzk35q",
+        "rev": "f6efca43715f3ccab5bb25674191d4d1994c3c6e",
+        "sha256": "0a0r7l3i1p9b4bpgmy6qd9mya6q5im2pr6w91z7v2y82437468i2",
         "type": "tarball",
-        "url": "https://github.com/dfinity/motoko-base/archive/822e35d4c167b34808301e00655f67a516053b44.tar.gz",
+        "url": "https://github.com/dfinity/motoko-base/archive/f6efca43715f3ccab5bb25674191d4d1994c3c6e.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "motoko-matchers": {