Update action references to new supertokens/actions monorepo

[porcellus]

The standalone action repos have been consolidated into supertokens/actions. Workflow files in this repo need to update their uses: references.

Files to update

Workflow	Old reference	New reference
.github/workflows/auth-react-test-1.yml	supertokens/auth-react-testing-action@main	supertokens/actions/auth-react-testing-action@main
.github/workflows/auth-react-test-1.yml	supertokens/extended-matrix-action@main	supertokens/actions/extended-matrix-action@main
.github/workflows/auth-react-test-3.yml	supertokens/auth-react-testing-action@main	supertokens/actions/auth-react-testing-action@main
.github/workflows/website-test.yml	supertokens/website-testing-action@main	supertokens/actions/website-testing-action@main
.github/workflows/backend-sdk-testing.yml	supertokens/backend-sdk-testing-action@main	supertokens/actions/backend-sdk-testing-action@main
.github/workflows/unit-test.yml	supertokens/get-supported-versions-action@main	supertokens/actions/get-supported-versions-action@main

Also update any setup sub-action references (e.g. supertokens/auth-react-testing-action/setup@main → supertokens/actions/auth-react-testing-action/setup@main).