[gitlab-ci] update lts to 18.18

2 jobs for 70-dev-searx-parser in 95 minutes and 55 seconds (queued for 4 seconds)
Status Job ID Name Coverage
  Test
failed #2613
docs

00:40:01

passed #2614
test

00:55:53

 
Name Stage Failure
failed
docs Test
    readGraphFromJson (src/Gargantext/Core/Viz/Graph.hs:251)
mergeGraphNgrams (src/Gargantext/Core/Viz/Graph.hs:258)
Completed 433 action(s).

-- While building package gargantext-0.0.4.9.5 (scroll up to its section to see the error) using:
/builds/gargantext/haskell-gargantext/.stack-root/setup-exe-cache/x86_64-linux/Cabal-simple_mPHDZzAJ_3.2.1.0_ghc-8.10.6 --builddir=.stack-work/dist/x86_64-linux/Cabal-3.2.1.0 haddock --html --hoogle --html-location=../$pkg-$version/ --haddock-option=--hyperlinked-source --haddock-option=--quickjump
Process exited with code: ExitFailure 1
Cleaning up file based variables
ERROR: Job failed: exit code 1