Allow dependabot in CLA check

Add dependabot[bot] to the allowlist so PRs that include dependabot
commits don't fail the CLA check.

Author: sgd2z

.github/workflows/cla.yaml

@@ -23,3 +23,4 @@ jobs:
           path-to-signatures: signatures.json
           remote-organization-name: secondlife
           remote-repository-name: cla-signatures
+          allowlist: dependabot[bot]