Allow a longer time for Pyk documentation builds (#4440)

Now that we're building a Docker environment for this job, it can hit
its time limit of 10 minutes easily:
https://github.com/runtimeverification/k/actions/runs/9481407834/job/26125129742

.github/workflows/release.yml

@@ -424,7 +424,7 @@ jobs:
     name: 'Build Pyk Documentation'
     needs: ubuntu-jammy
     runs-on: [self-hosted, linux, normal]
-    timeout-minutes: 10
+    timeout-minutes: 30
     steps:
       - name: 'Check out code'
         uses: actions/checkout@v4