chore: upgrade `api-server` Rock to 2.3.0 #137

Job	Run time
Get rocks modified and build-scan-test them / Get rockcraft paths modified / Get all rockcraft.yaml paths	8s
Get rocks modified and build-scan-test them / Get rockcraft paths modified / Get paths for ROCKs modified by PR	4s
Get rocks modified and build-scan-test them / build-scan-test-publish-rock (api-server) / build / Build api-server	10m 18s
Get rocks modified and build-scan-test them / build-scan-test-publish-rock (api-server) / integration-tests / Test api-server:2.3.0	6m 28s
Get rocks modified and build-scan-test them / build-scan-test-publish-rock (api-server) / sanity-tests / Sanity test api-server:2.3.0	43s
Get rocks modified and build-scan-test them / build-scan-test-publish-rock (api-server) / scan / Scan api-server:2.3.0	1m 12s
Get rocks modified and build-scan-test them / build-scan-test-publish-rock (api-server) / publish	0s
	18m 53s

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