Pin dependencies (#12)

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This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| [actions/checkout](https://togithub.com/actions/checkout) | action |
pinDigest | -> `b4ffde6` |
|
[docker/build-push-action](https://togithub.com/docker/build-push-action)
| action | pinDigest | -> `4a13e50` |
|
[docker/setup-buildx-action](https://togithub.com/docker/setup-buildx-action)
| action | pinDigest | -> `f95db51` |

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Author: jessemyers-lettuce

.github/workflows/pull-request.yaml

@@ -9,13 +9,13 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout source
-        uses: actions/checkout@v4
+        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4
 
       - name: Setup buildx
-        uses: docker/setup-buildx-action@v3
+        uses: docker/setup-buildx-action@f95db51fddba0c2d1ec667646a06c2ce06100226 # v3
 
       - name: Build container image
-        uses: docker/build-push-action@v5
+        uses: docker/build-push-action@4a13e500e55cf31b7a5d59a38ab2040ab0f42f56 # v5
         with:
           context: .
           file: Dockerfile