fix(ci): limit test parallelism on Linux to prevent OOM

TUnit runs tests in parallel by default, which can cause memory
pressure and OOM kills on Ubuntu runners. Add --maximum-parallel-tests 1
for Linux only to run tests sequentially.

This may increase test time but should prevent the silent process kills.

Author: Nucs

.github/workflows/build-and-release.yml

@@ -55,9 +55,14 @@ jobs:
         echo "Starting test run..."
         echo "dotnet version: $(dotnet --version)"
         echo "Available memory: $(free -h 2>/dev/null || echo 'N/A')"
+        # On Linux, limit parallelism to prevent OOM kills
+        MAX_PARALLEL=""
+        if [[ "$RUNNER_OS" == "Linux" ]]; then
+          MAX_PARALLEL="--maximum-parallel-tests 1"
+        fi
         dotnet run --project test/NumSharp.UnitTest/NumSharp.UnitTest.csproj \
           --configuration Release --no-build --framework net10.0 \
-          -- --treenode-filter '/*/*/*/*[Category!=OpenBugs]&/*/*/*/*[Category!=HighMemory]' --report-trx
+          -- --treenode-filter '/*/*/*/*[Category!=OpenBugs]&/*/*/*/*[Category!=HighMemory]' $MAX_PARALLEL --report-trx
 
     - name: Upload Test Results
       uses: actions/upload-artifact@v4