fix(ci): exclude HighMemory tests to prevent Ubuntu OOM kills

Root cause of Ubuntu CI failures:
- AllocationTests (marked [HighMemory]) allocates 4GB, 8GB, 16GB arrays
- The treenode-filter only excluded [OpenBugs], not [HighMemory]
- On Ubuntu/Linux, OOM killer silently terminates the process
- Windows/macOS handle OOM differently (managed exceptions or more swap)

The workflow comment mentioned HighMemory should be excluded but the
filter wasn't actually updated. Fixed by adding the HighMemory exclusion
using correct TUnit syntax: & operator between full filter expressions.

Filter syntax:
- Valid: '/*/*/*/*[Category!=A]&/*/*/*/*[Category!=B]'
- Invalid: '/*/*/*/*[Category!=A&Category!=B]'

Author: Nucs

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

@@ -57,7 +57,7 @@ jobs:
         echo "Available memory: $(free -h 2>/dev/null || echo 'N/A')"
         dotnet run --project test/NumSharp.UnitTest/NumSharp.UnitTest.csproj \
           --configuration Release --no-build --framework net10.0 \
-          -- --treenode-filter '/*/*/*/*[Category!=OpenBugs]' --report-trx
+          -- --treenode-filter '/*/*/*/*[Category!=OpenBugs]&/*/*/*/*[Category!=HighMemory]' --report-trx
 
     - name: Upload Test Results
       uses: actions/upload-artifact@v4