Update .gitlab-ci.yml

1 job for master in 6 seconds
Status Job ID Name Coverage
  Build
failed #32874
build-doc

00:00:06

 
Name Stage Failure
failed
build-doc Build
    @ Pkg.API /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/API.jl:77
[8] #develop#14
@ /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/API.jl:74 [inlined]
[9] develop(pkg::Pkg.Types.PackageSpec)
@ Pkg.API /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.6/Pkg/src/API.jl:74
[10] top-level scope
@ none:1
Cleaning up file based variables
ERROR: Job failed: exit code 1