Bump actions/download-artifact from 3 to 4

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v3...v4)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/deploy-lambda-function.yml

@@ -179,7 +179,7 @@ jobs:
         if: inputs.release-tag != ''
 
       - name: 'Pull artifact'
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: ${{ inputs.artifact-name }}
         # Only if we are pulling from an artifact

.github/workflows/register-task-definition.yml

@@ -210,7 +210,7 @@ jobs:
         continue-on-error: ${{ inputs.allow-datadog-to-fail }}
 
       - name: 'Download task-definition'
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: ${{ inputs.artifact-name }}