Updates copy from Premium to Upgrades.

[thijsoo]

Context

• We want to change some copy.

Summary

This PR can be summarized in the following changelog entry:

• Changes the copy in the admin sitebar from Premium to Upgrades

Relevant technical choices:

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Go to /wp-admin and make sure that in the Yoast SEO sidebar it says Upgrades and it leads to ?page=wpseo_licenses
• In the front-end inspector make sure that under SEO Settings it also says Upgrades and leads to ?page=wpseo_licenses

Relevant test scenarios

• [ ] Changes should be tested with the browser console open
• [ ] Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• [ ] Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• [ ] Changes should be tested on different browsers
• [ ] Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• [X] QA should use the same steps as above.

QA can test this PR by following these steps:

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

UI changes

• [x] This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Other environments

• [ ] This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

Documentation

• [ ] I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• [X] I have tested this code to the best of my abilities.
• [ ] During testing, I had activated all plugins that Yoast SEO provides integrations for.
• [ ] I have added unit tests to verify the code works as intended.
• [ ] If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• [ ] I have written this PR in accordance with my team's definition of done.
• [x] I have checked that the base branch is correctly set.

Innovation

• [X] No innovation project is applicable for this PR.
• [ ] This PR falls under an innovation project. I have attached the innovation label.
• [ ] I have added my hours to the WBSO document.

Fixes #

[coveralls]

Pull Request Test Coverage Report for Build 53daa8d291783f4c2d026ca29c6ab3c3fdf57336

Details

• 0 of 3 (0.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 52.638%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/integrations/admin/menu-badge-integration.php	0	1	0.0%
admin/menu/class-base-menu.php	0	2	0.0%
<!--	Total:	0	3

Totals
Change from base Build bce64cd247c6a27acec1d76069b69b2f7d7be199:	0.0%
Covered Lines:	28308
Relevant Lines:	54399

---

💛 - Coveralls

[hardikgohil7988]

@oksanayoast @tatasha2004 Verified this PR by checking Upgrade tab on backend and front end with correct URL.