chore(ci): bump GitHub Actions to Node 24 (#30)

## Summary

Bulk SHA-pin update of GitHub Actions to their latest Node-24-compatible
release. Pre-emptive migration ahead of GitHub Actions runner Node 20
removal in Fall 2026.

## Actions bumped

- `actions/checkout@v2` -> `df4cb1c0...` (v6.0.3)
- `EndBug/add-and-commit@v4` -> `290ea2c4...` (v10.0.0)

## Verification

Every emitted SHA was verified via `gh api
/repos/<owner>/<repo>/commits/<sha>` before commit.

## Background

Node 20 is being removed from GitHub Actions runners in Fall 2026 (see
[GitHub
changelog](https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/)).
This PR pre-emptively bumps every pinned third-party action to its first
Node-24-compatible release so the workflows keep running on the new
runner default.

Author: shanesavoie

.github/workflows/workflow.yml

@@ -12,7 +12,7 @@ jobs:
     # Steps represent a sequence of tasks that will be executed as part of the job
     steps:
     # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
       with:
         ref: "traffic"
 
@@ -24,7 +24,7 @@ jobs:
 
     # Commits files to repository
     - name: Commit changes
-      uses: EndBug/add-and-commit@v4
+      uses: EndBug/add-and-commit@290ea2c423ad77ca9c62ae0f5b224379612c0321 # v10.0.0
       with:
         author_name: Traffic Bot
         message: "GitHub traffic"