Update playground and blueprints to use WP 7.0

[jeffpaul]

Description

Playground appears to still be using 7.0 RC5, when it should be using the released version of 7.0. I suspect this may be from:

ai/.wordpress-org/blueprints/blueprint.json

Line 6 in 485c884

"wp": "beta"

and:

ai/.github/workflows/pr-playground-preview.yml

Lines 85 to 87 in 485c884

	preferredVersions: {
	wp: 'beta',
	},

So perhaps updating there will ensure our Live Preview on WPORG and the Playground PR environments properly load 7.0?

Step-by-step reproduction instructions

Test on a PR or on WPORG live preview and see WP 7.0 RC5 loads instead of 7.0

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except the AI plugin.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure

[dkotter]

Note there are also a handful of other places we could look to update as well now that 7.0 is out:

• Plugin check workflow we updated from latest to trunk so it would pass (see 8a3bb69#diff-af8392ca8fff1c1e3466ad30d3c848cb3b0dcbcd8fc8bd2f030c30af237930c1L64)
• Our PHPUnit test workflow used to run on latest and trunk but we removed latest from our matrix (see 8a3bb69#diff-faff1af3d8ff408964a57b2e475f69a6b7c7b71c9978cccc8f471798caac2c88L163)
• Our .wp-env config files used to have core set to null but we changed that to WordPress/WordPress#master (see 8a3bb69#diff-9fd21b09a0144355cfd001e3952767df08b2e04241994470aa1d627f797b171eL3)