Leap seconds cause differences in IC7 output

[szarnyasg]

The output of SNB Interactive's Q7 is sensitive to leap second support.

According to wikipedia, there was a leap second on June 30, 2012, which is part of our data set.

Some systems (DuckDB, SQL Server, etc.) support leap seconds, while others (e.g. Neo4j) use UTC-SLS instead:

https://neo4j.com/docs/cypher-manual/current/syntax/temporal/

Cypher does not support leap seconds; UTC-SLS (UTC with Smoothed Leap Seconds) is used to manage the difference in time between UTC and TAI (International Atomic Time).

We need to decide how to handle this in the specification.
My suggestion would be to be lenient and allow a difference of +/- 1 minute.

The said, this difference can uncover interesting bugs as it did for DuckDB's cast function:
ldbc/ldbc_snb_interactive_v1_impls@d3de117

cc @GLaDAP