Redmine

GitHub CI has become unstable since this workflow run:
https://github.com/redmine/redmine/actions/runs/27570214341/job/81504469992

Some matrix jobs now hit the 6-hour timeout after starting the test suite:

# Running:

sh: 1: pandoc: not found
sh: 1: pandoc: not found
sh: 1: pandoc: not found
DEPRECATION WARNING: GroupsController#remove_user is deprecated and will be removed in Redmine 8.0. Please use #remove_users instead. (called from sudo_mode at /home/runner/work/redmine/redmine/lib/redmine/sudo_mode.rb:78)
Error: The operation was canceled.

The root cause is still unclear, but it may be related to the parallel test enablement in r24718 combined with changes introduced by r24758.

To prioritize CI stability, this reverts the CI parallel test enablement from r24718.

Based on several test runs, the workflow seems to pass with parallel tests disabled:
https://github.com/hidakatsuya/redmica/actions/runs/27586838988

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 8f6de5ed2..ac1943d5e 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -52,9 +52,6 @@ jobs:
           db-type: ${{ matrix.db }}
           ruby-version: ${{ matrix.ruby }}

-      - name: Enable parallel tests
-        run: echo "PARALLEL_WORKERS=$(nproc)" >> $GITHUB_ENV
-
       - name: Run tests
         run: |
           bin/rails test