Update PostgreSQL JDBC driver to version 42.7.8

[coderabbitai]

Description

Update the PostgreSQL JDBC driver version in the Debezium tutorial from 42.5.4 to 42.7.8 (latest stable).

Location

docs/integrate/debezium/tutorial.md:148

Replace:

postgresql-42.5.4.jar

With:

postgresql-42.7.8.jar

Context

This issue was created based on a review suggestion in PR #289.

References:

• PR: Debezium: Tutorial about replicating data from MSSQL #289
• Requested by: @amotl

[amotl]

See also #281 (review):

68-68: Align PostgreSQL JDBC driver versions across documentation.

Currently, spark/usage.md references 42.6.0, databricks/azure-databricks.md uses 42.2.23, and tableau/index.md mentions 42.7.1. Choose a single, up-to-date version (for example, the latest stable 42.7.x) or document why different contexts require different drivers.