ci-test.yml: add Hugo 0.86.1

Adding it to tests does nothing for us in practice. Right now, it's a reminder for me that `.IsMenuCurrent` acts
differently in Hugo 0.86.0 (or later) than before and may require manual intervention from users.

Author: Vimux

.github/workflows/ci-test.yml

@@ -40,6 +40,7 @@ jobs:
           - '0.59.1' # last major version without goldmark renderer
           - '0.60.1' # first major version with goldmark renderer
           - '0.76.5' # https://github.com/gohugoio/hugo/issues/7822
+          - '0.86.1' # https://github.com/gohugoio/hugo/issues/9150
           - 'latest'
       fail-fast: true