pw.io.airbyte.read: allow users to override connector dependency versions

[zxqfd555]

Is your feature request related to a problem? Please describe.
Airbyte connectors available as PyPI packages often declare their dependencies without version upper bounds or exact pins. This means that installing a connector at any point in time may pull in a different (and potentially incompatible) version of a transitive dependency compared to what was installed previously.

The correct long-term fix is upstream: connector maintainers should pin their dependencies properly. However, that fix may be slow to arrive — or may never come for some connectors. In the meantime, users of pw.io.airbyte.read have no way to stabilize their environment without forking or monkey-patching the connector package itself.

A concrete recent example: airbyte-cdk removed MessageRepresentationAirbyteTracedErrors in a non-backward-compatible release, which broke airbyte-source-github and several other connectors. Because no version pin was in place, this cascaded immediately to the users and integration tests.

Describe the solution you'd like
Add an optional dependency_overrides parameter to pw.io.airbyte.read that allows users to specify additional pip constraints to apply when installing the connector. For example:

pw.io.airbyte.read(
    ...,
    dependency_overrides=["airbyte-cdk==X.Y.Z"],
)

This would allow users to:

• Pin a known-good version of a broken transitive dependency
• Unblock a pipeline immediately, without waiting for an upstream fix
• Reproduce a stable environment on repeated runs

Describe alternatives you've considered

• Waiting for upstream connector fixes — not always timely, and sometimes the fix never comes.
• Vendoring / forking the connector — disproportionate effort for what should be a simple version pin.
• Full environment pinning at the project level — works in some setups, but conflicts with how pw.io.airbyte.read dynamically installs connectors.