Update continuous.yml (#2161)

.github/workflows/continuous.yml

@@ -136,7 +136,7 @@ jobs:
             -DLIBIGL_COPYLEFT_CGAL=ON ^
             -B build ^
             -S .
-          cmake --build build -j1
+          cmake --build build -j2
 
       - name: Tests
         run: cd build; ctest --verbose -j2