Update cpu.pinned_env.in for pinning plotly

Author: bhavya2109sharma

build_artifacts/v3/v3.1/v3.1.1/cpu.pinned_env.in

@@ -4,3 +4,4 @@ conda-forge::catboost[version='>=1.1.1,<1.3.0',build='*cpu*']
 conda-forge::libsqlite[version='<3.49.0']
 conda-forge::urllib3[version='<2']
 conda-forge::papermill[version='>=2.6.0']
+conda-forge::'plotly[version='<6.1.0']