niv motoko-base: update dfabfc32 -> 93583552 (#4568)

## Changelog for motoko-base:
Branch: next-moc
Commits: [dfinity/motoko-base@dfabfc32...93583552](dfinity/motoko-base@dfabfc3...9358355)

* [`e4d32622`](dfinity/motoko-base@e4d3262) Code Refactoring: Curate More Unused Declarations ([dfinity/motoko-base⁠#636](https://togithub.com/dfinity/motoko-base/issues/636))

nix/sources.json

@@ -75,10 +75,10 @@
         "homepage": null,
         "owner": "dfinity",
         "repo": "motoko-base",
-        "rev": "dfabfc3201950263a0057f5d1a78d2ede5c87478",
-        "sha256": "1wd9rcmhg82h08l3gz3gmn2xpgalvf679w7yz2g35yzbg2b5g2fd",
+        "rev": "935835525c76312a11207dc9ae268475db867271",
+        "sha256": "0hnnb808ppggxq5g4bha3zq5mb7ygck994dh1ki09nj2brj4ml7h",
         "type": "tarball",
-        "url": "https://github.com/dfinity/motoko-base/archive/dfabfc3201950263a0057f5d1a78d2ede5c87478.tar.gz",
+        "url": "https://github.com/dfinity/motoko-base/archive/935835525c76312a11207dc9ae268475db867271.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "motoko-matchers": {