chore(deps): update kibana-openapi-spec digest to a8e3b64 (#1428)

Co-authored-by: elastic-renovate-prod[bot] <174716857+elastic-renovate-prod[bot]@users.noreply.github.com>

Author: elastic-renovate-prod[bot]

generated/kbapi/Makefile

@@ -2,7 +2,7 @@
 SHELL := /bin/bash
 ROOT_DIR := $(shell dirname $(realpath $(firstword $(MAKEFILE_LIST))))
 
-github_ref ?= de217ef5b84c812b4c7c7848405fdf418d50f988
+github_ref ?= a8e3b6461fa27900deb3cb96f649506a922d1c0e
 oas_url    := https://raw.githubusercontent.com/elastic/kibana/$(github_ref)/oas_docs/output/kibana.yaml
 
 .PHONY: all