Fix Parse.ly Content API compatibility

[adamehirsch]

Sat down with my little robot friends to try and fix #281 .

• wp-parsely 3.17 removed the legacy Analytics_Posts_API class.
• wp-curate now supports wp-parsely 3.20.4 and later, using its Content API service.
• Converts comma-separated tags to the arrays expected by the Content API.
• Uses scalar section values, as required by wp-parsely 3.20.4+.
• Preserves existing cache keys and public filter arguments.
• Uses the already-validated $parsely instance instead of rereading $GLOBALS.
• Adds regression coverage for the 3.20.4 version boundary and empty tag values.

Testing

• PHPCS passed.
• PHPStan passed with no errors.
• PHPUnit passed: 22 tests and 108 assertions.
• Confirmed the ProPublica VIP local environment loads wp-parsely 3.24.1 and exposes the Content API service.

[mogmarsh]

@adamehirsch Thanks for the submission!
This looks good, and I'm approving it...
However, if you feel up for it, I wouldn't mind a few changes. We are fine with only supporting wp-parsely 3.20.4 and later (because that version is already over a year old), so the PR could be updated to return early if the plugin doesn't exist or it's older than 3.20.3. This should simplify things a lot. If you're not up for it, let me know and I'll merge this in, or bring it into our repo and make the changes myself.
Let me know if you have any questions.

Thanks!

[adamehirsch]

@mogmarsh --

I'm totally fine to make the change -- won't that mean that upgrading will require us to bump both this and wp-parsely in rapid succession, as wp-curate will start returning early with our current (outdated) wp-parsely? Can we upgrade them both in one PR or will we have to make the changes atomically?

[kevinfodness]

@adamehirsch we can upgrade them both in one PR and test the effects.

[adamehirsch]

Updated to require wp-parsely 3.20.4+. This removes the legacy client fallback and pre-3.20.4 section conversion while retaining Content API tag normalization. We'll expect to test and update wp-curate and wp-parsely together in one PR, once Alley endorses.

[adamehirsch]

Dependabot check seems to have skipped for some reason, but this is ready to check/deploy from my side, @mogmarsh