Fix syntax error

Author: rhornung67

Dockerfile

@@ -15,7 +15,7 @@ FROM ghcr.io/llnl/radiuss:ubuntu-22.04-gcc-13 AS gcc13
 ENV GTEST_COLOR=1
 COPY . /home/raja/workspace
 WORKDIR /home/raja/workspace/build
-RUN cmake -DCMAKE_CXX_COMPILER=g++ --DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On .. && \
+RUN cmake -DCMAKE_CXX_COMPILER=g++ -DCMAKE_BUILD_TYPE=Release -DRAJA_ENABLE_WARNINGS=On -DRAJA_ENABLE_WARNINGS_AS_ERRORS=On -DENABLE_OPENMP=On .. && \
     make -j 16 &&\
     ctest -T test --output-on-failure