fix: coerce some types from query result set

[ntnhaatj]

Description

when running dbt source freshness the result could not be coerced to timestamp from response strings

^[[0m06:33:28.268707 [error] [MainThread]: ^[[33mDatabase Error in source bnpl_transaction_get_offers_stag_schema_id_163 (models/bnpl/sources.yml)^[[0m^[[0m06:33:28.268883 [error]
[MainThread]:   Expected a timestamp value when querying field 'ingestion_time' of table bnpl.bnpl_transaction_get_offers_stag_schema_id_163 but received value of type 'str' instead

noticed that from v0.20 dbt-core has been updated to prevent using agate table coercion from SQL adapter query result (dbt-labs/dbt-core#3499)

this PR aims to support the coercion for timestamp type from livy query result set

Checklist

• I have read the contributing guide and understand what's expected of me
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• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
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• I have run changie new to create a changelog entry