Pin Poco away from 1.14.0

[cailafinn]

Description of work

Summary of work

Breaking change to HTTPSClientSession in latest Poco version. Pin it to stop this happening.

https://raw.githubusercontent.com/pocoproject/poco/poco-1.14.0-release/CHANGELOG

There is no associated issue.

To test:

1. Builds should complete successfully on all OSs.

This does not require release notes because **there are no user-facing changes. **

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[SilkeSchomann]

I can confirm that all tests pass with the new pin for poco.