Make the build run in no more than 4 processes in parallel.

.github/workflows/run_tests.yml

@@ -57,7 +57,7 @@ jobs:
       - name: Cmake and build
         env:
           CMAKE_ARGS: "
-            -DCMAKE_BUILD_TYPE=Debug
+            -DCMAKE_BUILD_TYPE=Release
             -DBUILD_SHARED_LIBS=FALSE
             -DBUILD_TESTS=TRUE
             -DZK_PLACEHOLDER_PROFILING=TRUE
@@ -85,6 +85,7 @@ jobs:
     needs: [checkout]
     strategy:
       fail-fast: false
+      max-parallel: 4 # don't run more than 4 jobs in parallel, they run out of memory
       matrix:
         target: [
             crypto3_zk_commitment_fold_polynomial_test,
@@ -135,7 +136,7 @@ jobs:
 
       - name: Build
         working-directory: ./build
-        run: cmake --build . -t ${{ matrix.target }} -j 1
+        run: cmake --build . -t ${{ matrix.target }}
 
       - name: Run test
         working-directory: ./build