Fix Linux build OOM and upgrade to gcc-13

- Limit make parallelism to -j4 to avoid OOM on GitHub runners (7GB RAM)
- Upgrade Linux build from gcc-11 to gcc-13 (better C++20 support)
- Matches local development environment (gcc-13)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: lums658

.github/workflows/build_cmake.yml

@@ -1,6 +1,6 @@
 # Workflow to configure with cmake and build with gcc
 
-name: Build with gcc-11
+name: Build with gcc-13
 
 on:
   push:
@@ -31,9 +31,10 @@ jobs:
           | sudo tee /etc/apt/sources.list.d/oneAPI.list
         sudo apt-get update
         DEBIAN_FRONTEND=noninteractive sudo apt-get -y install intel-oneapi-tbb-devel
-        # Install gcc-11 (available on ubuntu-22.04+)
-        DEBIAN_FRONTEND=noninteractive sudo apt-get -y install gcc-11 g++-11
-        sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-11 90 --slave /usr/bin/g++ g++ /usr/bin/g++-11
+        # Install gcc-13
+        sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test
+        DEBIAN_FRONTEND=noninteractive sudo apt-get -y install gcc-13 g++-13
+        sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-13 90 --slave /usr/bin/g++ g++ /usr/bin/g++-13
         sudo update-alternatives --install /usr/bin/cc cc /usr/bin/gcc 30
         sudo update-alternatives --install /usr/bin/c++ c++ /usr/bin/g++ 30
 
@@ -43,12 +44,13 @@ jobs:
         mkdir build
         cd build
         export TBBROOT=/opt/intel/oneapi/tbb/latest
-        cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_CXX_COMPILER=g++-11 -DNWGRAPH_BUILD_DOCS=OFF -DNWGRAPH_BUILD_TESTS=ON
+        cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo -DCMAKE_CXX_COMPILER=g++-13 -DNWGRAPH_BUILD_DOCS=OFF -DNWGRAPH_BUILD_TESTS=ON
 
     - name: make
       run: |
         cd NWgr/build
-        make -j -k
+        # Limit parallelism to avoid OOM on GitHub runners (7GB RAM)
+        make -j4 -k
 
     - name: run_test
       run: |

.github/workflows/build_cmake_mac.yml

@@ -47,7 +47,8 @@ jobs:
     - name: make
       run: |
         cd NWgr/build
-        make -j -k
+        # Limit parallelism to avoid potential OOM issues
+        make -j4 -k
 
     - name: run_test
       run: |