chore: bump GitHub Actions to current major versions (#35)

## Summary

Pure version bumps for the four GitHub Actions referenced under
`.github/workflows/`. No behavior change — actions are pinned to current
majors (or the current SHA, in the case of the third-party publish
action).

| File | Action | Before | After |
|---|---|---|---|
| `github-actions.yml`, `coverage.yml`, `python-publish.yml`,
`codeql-analysis.yml` | `actions/checkout` | `@v3` | `@v5` |
| `github-actions.yml`, `coverage.yml`, `python-publish.yml` |
`actions/setup-python` | `@v3` | `@v5` |
| `codeql-analysis.yml` |
`github/codeql-action/{init,autobuild,analyze}` | `@v2` | `@v3` |
| `python-publish.yml` | `pypa/gh-action-pypi-publish` | old SHA |
`v1.14.0` SHA + version comment |

## Why now

The `@v3` actions ran on the **Node 16 runtime**, which reached
end-of-life in 2023 and is on borrowed time on GitHub-hosted runners.
`@v5` (and `codeql-action @v3`) all use Node 20, the current supported
runtime. We were also missing security/bug fixes shipped in newer
majors.

## Conventions used

- First-party actions (`actions/*`, `github/*`) → floating major-version
tag (`@v5`, `@v3`). Standard for first-party, low supply-chain risk.
- Third-party action (`pypa/gh-action-pypi-publish`) → stays SHA-pinned
for supply-chain safety. The trailing `# v1.14.0` comment makes the
human-readable version visible without sacrificing the immutable pin.

Closes #34

1 files changed, 2 insertions, 2 deletions

diff --git a/.github/workflows/github-actions.yml b/.github/workflows/github-actions.yml
index 1c20599..1af692a 100644
--- a/.github/workflows/github-actions.yml
+++ b/.github/workflows/github-actions.yml
@@ -156,10 +156,10 @@ jobs:
             tox_env: 'py314'
             os: 'macos-latest'
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v5
       with:
         fetch-depth: 0
-    - uses: actions/setup-python@v3
+    - uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python }}
         architecture: ${{ matrix.python_arch }}