Pin arviz dependency to < 0.20.0

PiperOrigin-RevId: 877512756

Author: andyl7an

CHANGELOG.md

@@ -23,6 +23,9 @@ To release a new version (e.g. from `1.0.0` -> `2.0.0`):
 
 ## [Unreleased]
 
+* Pin `arviz` dependency to `< 0.20.0` to fix upstream `InferenceData`
+  deprecation.
+
 ## [1.5.2] - 2026-02-10
 
 * Move `schema` package as `meridian.schema`.

pyproject.toml

@@ -24,7 +24,7 @@ keywords = [
 # pip dependencies of the project
 # Installed locally with `pip install -e .`
 dependencies = [
-  "arviz",
+  "arviz < 0.20.0",
   "altair >= 5",
   "bidict",
   "immutabledict",