Readme: bump all the example versions to v7

[danwkennedy]

No description provided.

[Copilot]

Pull request overview

Updates the README’s workflow snippets to reference the new major version of actions/upload-artifact, aligning the documentation examples with the action’s v7 release in this repository.

Changes:

• Bump all actions/upload-artifact@v4 references in README examples to @v7.

Show a summary per file

File	Description
README.md	Updates all README example uses: lines to actions/upload-artifact@v7.

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Comments suppressed due to low confidence (2)

README.md:260

• This section’s narrative describes behavior as “not supported with v4”, but the example directly below now uses actions/upload-artifact@v7. If the behavior applies to v7 as well, the text should be updated to say v4+/v7+ to avoid implying it’s specific to v4.

Unlike earlier versions of `upload-artifact`, uploading to the same artifact via multiple jobs is _not_ supported with `v4`.

```yaml
- run: echo hi > world.txt
- uses: actions/upload-artifact@v7
  with:

README.md:294

• In the matrix example, the workflow step now uses actions/upload-artifact@v7, but the surrounding explanation still references “Artifacts created by upload-artifact@v4 are immutable.” Consider updating the wording to v4+/v7+ (or otherwise clarifying) so the prose matches the version used in the example.

      run: ./some-script --version=${{ matrix.version }} > my-binary
    - name: Upload
      uses: actions/upload-artifact@v7
      with:
        name: binary-${{ matrix.os }}-${{ matrix.version }}
        path: my-binary

• Files reviewed: 1/1 changed files
• Comments generated: 1

[Copilot]

README examples were bumped to actions/upload-artifact@v7, but the WARNING at the top of the README still tells users to update to v4 (and GHES section references v4+). This makes the guidance inconsistent—please update the surrounding README text to refer to v7 (or v7+ / v4+ consistently) so users know which major version is recommended.

This issue also appears in the following locations of the same file:

• line 255
• line 289