fix: normalize postgres UUIDs to strings

[emagda97]

Description

Fixes a bug where PostgreSQL UUID columns were being serialized as numerical arrays (e.g., [1, 158, 103, ...]) in JSON output instead of standard hyphenated strings.

Root Cause
The generic results.Values() method in the pgx driver returns UUIDs as [16]byte fixed arrays. Go's standard encoding/json package serializes fixed arrays of bytes as numerical arrays rather than strings.

Solution
Introduced a centralized NormalizeValue helper function in internal/sources/util.go that intercepts values based on their PostgreSQL Object Identifier (OID). If it detects a UUID OID (2950) and a [16]byte type, it converts it into a standard UUID string via the github.com/google/uuid package.

Impact
Consistent string serialization for UUIDs across all Postgres-compatible drivers (postgres, alloydb-postgres, cloud-sql-postgres, yugabytedb). Added unit tests to internal/sources/util_test.go to guarantee reliability.

PR Checklist

• Make sure you reviewed CONTRIBUTING.md
• Make sure to open an issue as a bug/issue before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)
• Make sure to add ! if this involve a breaking change

🛠️ Fixes #3795

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[gemini-code-assist]

Code Review

This pull request introduces a NormalizeValue utility function to convert PostgreSQL UUID values (OID 2950) from [16]byte to their string representation, applying it across AlloyDB, Cloud SQL Postgres, Postgres, and YugabyteDB sources. It also adds corresponding unit tests. The review feedback suggests extending this normalization to support PostgreSQL UUID arrays (OID 2951) and provides the necessary code and test cases to implement this improvement.

[emagda97]

also included some Zizmor workflow fixes under .github because the presubmit tests were failing.