Bump vws-python-mock to 2026.2.15.4

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

Author: adamtheturtle

pyproject.toml

@@ -77,7 +77,7 @@ optional-dependencies.dev = [
     "ty==0.0.16",
     "types-requests==2.32.4.20260107",
     "vulture==2.14",
-    "vws-python-mock==2026.2.15",
+    "vws-python-mock==2026.2.15.4",
     "vws-test-fixtures==2023.3.5",
     "yamlfix==1.19.1",
     "zizmor==1.22.0",