bot: Update snsdemo to release-2024-12-25 (#6080)

# Motivation
We would like to keep the testing environment, provided by snsdemo, up
to date.

# Changes
* Updated `snsdemo` version in `dfx.json`.
* Ensured that the `dfx` version in `dfx.json` matches `snsdemo`.

# Tests
CI should pass.

Co-authored-by: gix-bot <gix-bot@users.noreply.github.com>

dfx.json

@@ -442,7 +442,7 @@
         "DIDC_VERSION": "didc 0.4.0",
         "POCKETIC_VERSION": "3.0.1",
         "CARGO_SORT_VERSION": "1.0.9",
-        "SNSDEMO_RELEASE": "release-2024-12-18",
+        "SNSDEMO_RELEASE": "release-2024-12-25",
         "IC_COMMIT_FOR_PROPOSALS": "release-2024-12-06_03-16-base",
         "IC_COMMIT_FOR_SNS_AGGREGATOR": "release-2024-12-06_03-16-base"
       },