ci: update GitHub Actions to current major versions

[magnus-madsen]

Every action used by the workflows was pinned several majors behind. This brings them all current.

Workflow	Action	Was	Now
ci.yml	actions/checkout (4 uses)	v4	v7
ci.yml	actions/setup-node (3 uses)	v4	v7
ci.yml	actions/setup-java	v4	v5
publish-open-vsx.yaml	actions/checkout, actions/setup-node	v4	v7
semantic-commit.yaml	actions/github-script	v4	v9

github-script@v4 was the pressing one. It declares runs.using: node12, a runtime GitHub retired, and only still ran because the runner silently forced it onto a newer Node — a fallback that can disappear without warning.

Also drops the github-token input from the title check (the script makes no API calls, so it never needed a token) and removes two trailing whitespace-only lines.

Why this should be a no-op

Checked against the release notes for each major crossed:

• checkout v7 blocks fork-PR checkout only for pull_request_target and workflow_run. These workflows use plain pull_request.
• setup-node v5+ introduced auto-caching keyed off a packageManager field in package.json, which this repo does not set — and every call site already passes cache: 'npm' explicitly.
• github-script v9 breaks require('@actions/github') and redeclaring getOctokit. The title-check script does neither; it only reads context.payload.pull_request.title and process.env.regex.
• node24 runtime (checkout v5+, setup-java v5, github-script v8+) needs runner >= v2.327.1. GitHub-hosted runners are well past that.

Verification

Locally: all four YAML files parse, no @v4 pins remain, and the folded github-script body was syntax-checked and run against the job's regex — fix: something and chore: deps pass, nope no prefix and feat:missing space are rejected. Unchanged from before.

Beyond that this is reasoning from changelogs rather than a green run. CI on this PR is the real test, and it exercises every changed action except the Open VSX publish path, which is tag-triggered and won't run here.

🤖 Generated with Claude Code