Update Documenter.yml

Added GKSwstype: "100" in the `env`.

Author: BoundaryValueProblems

.github/workflows/Documenter.yml

@@ -19,4 +19,5 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} # For authentication with GitHub Actions token
           DOCUMENTER_KEY: ${{ secrets.DOCUMENTER_KEY }} # For authentication with SSH deploy key
+          GKSwstype: "100" # https://discourse.julialang.org/t/generation-of-documentation-fails-qt-qpa-xcb-could-not-connect-to-display/60988
         run: julia --project=docs/ docs/make.jl