Fix wrong executable and missing Werror flag in CI test (ECP-WarpX#3964)

* change executable from warpx.3d to warpx.rz in order to run a rz simulation

* add -Werror before compiling WarpX in CI test

.github/workflows/ubuntu.yml

@@ -106,6 +106,11 @@ jobs:
           ccache-openmp-3D-RZ-SP-
     - name: build WarpX
       run: |
+
+        # we need to define this *after* having installed the dependencies,
+        # because the compilation of blaspp raises warnings.
+        export CXXFLAGS="-Werror"
+
         cmake -S . -B build                 \
           -GNinja                           \
           -DCMAKE_VERBOSE_MAKEFILE=ON       \
@@ -118,7 +123,7 @@ jobs:
 
         cmake --build build -j 2
         ./build/bin/warpx.3d Examples/Physics_applications/laser_acceleration/inputs_3d
-        ./build/bin/warpx.3d Examples/Physics_applications/laser_acceleration/inputs_rz
+        ./build/bin/warpx.rz Examples/Physics_applications/laser_acceleration/inputs_rz
 
   build_gcc_ablastr:
     name: GCC ABLASTR w/o MPI