Implicit Date conversion clashes with DateTime scalar

If `DateTime` scalar from `graphql-java-extended-scalars` is used which maps to the `OffsetDateTime` Java type the following exception is thrown.

```
org.springframework.dao.InvalidDataAccessApiUsageException: Parameter value [Thu Dec 03 01:00:00 CET 2020] did not match expected type [java.time.OffsetDateTime (n/a)]
```

Implicit Date conversion should be removed from `FilterExpressionParser`.

Start in FilterExpressionParser and inspect the implicit Date conversion used with the graphql-java-extended-scalars DateTime scalar mapped to OffsetDateTime. Reproduce the reported InvalidDataAccessApiUsageException, then verify that removing this conversion prevents the type mismatch for OffsetDateTime values.

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