Revert "🧪 Disable pytest-xdist in CI on Ubuntu ARM"

This reverts commit a43317f.

Author: webknjaz

.github/workflows/reusable-tests.yml

@@ -299,11 +299,6 @@ jobs:
         --parallel-live
         --skip-missing-interpreters false
         -qq
-        ${{
-          contains(inputs.runner-vm-os, 'arm')
-          && '-- -n0'
-          || ''
-        }}
     - name: Produce markdown test summary from JUnit
       if: always()
       uses: test-summary/[email protected]
@@ -321,7 +316,6 @@ jobs:
         --skip-pkg-install
         --
         --no-cov -vvvvv --lf
-        -n0
         && exit 1
       shell: bash
     - name: Send coverage data to Codecov