chore: pin Vale in GitHub action to last v2 vale version until we update to v3

[lornajane]

What/Why/How?

Vale has a new release (yay!) but it came with some directory structure changes and these are causing the build to fail. This pull request pins to a working version and I'll follow up with another one to handle the v3 update.

Check yourself

• Code is linted
• Tested with redoc/reference-docs/workflows (internal)
• All new/updated code is covered with tests

Security

• Security impact of change has been considered
• Code follows company security practices and guidelines

[changeset-bot]

⚠️ No Changeset found

Latest commit: 38d07b8

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[github-actions]

Command	Mean [s]	Min [s]	Max [s]	Relative
redocly lint packages/core/src/benchmark/benches/rebilly.yaml	1.066 ± 0.033	1.034	1.149	1.00
redocly-next lint packages/core/src/benchmark/benches/rebilly.yaml	1.070 ± 0.015	1.042	1.092	1.00 ± 0.03

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟡	Statements	76.31%	4100/5373
🟡	Branches	66.29%	2183/3293
🟡	Functions	68.42%	663/969
🟡	Lines	76.51%	3847/5028

Test suite run success

671 tests passing in 94 suites.

Report generated by 🧪jest coverage report action from 38d07b8