Update cmake-single-platform.yml

Add missing sudo

.github/workflows/cmake-single-platform.yml

@@ -31,7 +31,7 @@ jobs:
       # Configure CMake in a 'build' subdirectory. `CMAKE_BUILD_TYPE` is only required if you are using a single-configuration generator such as make.
       # See https://cmake.org/cmake/help/latest/variable/CMAKE_BUILD_TYPE.html?highlight=cmake_build_type
       run: |
-        apt-get install libgsl-dev
+        sudo apt-get install libgsl-dev
         cmake -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=${{env.BUILD_TYPE}}
 
     - name: Build