chore(changelog): open 0.25.4

0.25.3 shipped with its two entries — the verified-confirmation fix and the
native SPID rotator — and they are two separate subjects, so there was nothing
to merge this time.

Version constants untouched: the release script owns them, and it already
bumped them to 0.25.3 in the commit before this one.

changelog.json

@@ -1,4 +1,10 @@
 [
+  {
+    "version": "0.25.4",
+    "date": "",
+    "en": [],
+    "fr": []
+  },
   {
     "version": "0.25.3",
     "date": "",