chore(DEVA11Y-657): bump pinned CLI to 1.5.1

1.5.1 ships the --pr-scan additions consumed by this action: the machine-readable
[deva11y-result] stdout line (populates the error/warning/findings-count +
comment-url outputs) and --ai-agent forwarding. Bumps the CLI_VERSION pin from
1.5.0 so the action's outputs and the ai-agent mention activate.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: Crash0v3rrid3

action.yml

@@ -266,7 +266,7 @@ runs:
         AI_AGENT: ${{ inputs.ai-agent }}
       run: |
         set -euo pipefail
-        CLI_VERSION="1.5.0"
+        CLI_VERSION="1.5.1"
         # Optional AI remediation hand-off (validated above).
         AGENT_ARGS=()
         if [ -n "${AI_AGENT}" ]; then AGENT_ARGS=(--ai-agent "${AI_AGENT}"); fi