Fix: harden ValidationInfo.data access for Pydantic 2.13 compat #3550

Job	Run time
test-vscode	56s
changes	8s
test-dbt-versions (1.4)	1m 21s
test-dbt-versions (1.3)	1m 24s
test-dbt-versions (1.6)	1m 24s
test-dbt-versions (1.7)	1m 25s
test-dbt-versions (1.9)	1m 24s
test-dbt-versions (1.5)	1m 25s
test-dbt-versions (1.10)	1m 24s
test-dbt-versions (1.8)	1m 25s
test-vscode-e2e	0s
cicd-tests-windows	19s
doc-tests	56s
migration-test	56s
style-and-cicd-tests (3.11)	56s
style-and-cicd-tests (3.12)	56s
style-and-cicd-tests (3.9)	56s
style-and-cicd-tests (3.13)	56s
style-and-cicd-tests (3.10)	56s
engine-tests-docker (mysql)	13s
engine-tests-docker (postgres)	56s
engine-tests-docker (risingwave)	56s
engine-tests-docker (mssql)	56s
engine-tests-docker (trino)	56s
engine-tests-docker (clickhouse)	56s
engine-tests-docker (duckdb)	56s
engine-tests-docker (spark)	56s
ui-style	0s
ui-test	0s
engine-tests-cloud	1s
	25m 53s

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