chore(ci): bump GitHub Actions to Node 24 (#44)

## 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@8e8c483d…` (v6.0.1) → `df4cb1c0…` (v6.0.3)
- `actions/setup-node@395ad326…` (v6.1.0) → `48b55a01…` (v6.4.0)
- `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/ci.yml

@@ -8,12 +8,12 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out repository code
-        uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
+        uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
         with:
           submodules: 'true'
 
       - name: Install Node
-        uses: actions/setup-node@395ad3262231945c25e8478fd5baf05154b1d79f # v6.1.0
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
 
       - name: Install dependencies
         run: npm install

.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"