Upgrade gitlab-ci to 0.9.0 on lts/ghc-9.0.x

Update gitlab-ci flake input to version 0.9.0.

Changes

Upgrade gitlab-ci to 0.9.0

• Fix for cachix module to push actual outputs instead of .drv files
• Use om ci run --results=om.json to generate JSON with store paths
• Extract paths from JSON using jq -r '.result.ROOT.build.outPaths[]'
• Pipe extracted paths to cachix push via xargs
• Previous approach failed because omnix only outputs JSON file path to stdout
• The JSON contains actual store paths under the ROOT subflake

This ensures that built artifacts are properly pushed to the horizon cachix cache.

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