CI: use older version of emsdk because clang-19 has some bug

Author: Pascal Guenther

.github/workflows/webapp.yml

@@ -12,7 +12,7 @@ jobs:
     - uses: actions/checkout@v2
 
     - name: install emscripten
-      run: git clone https://github.com/emscripten-core/emsdk.git && emsdk/emsdk install latest && emsdk/emsdk activate latest && source emsdk/emsdk_env.sh
+      run: git clone https://github.com/emscripten-core/emsdk.git && emsdk/emsdk install 3.1.49 && emsdk/emsdk activate 3.1.49 && source emsdk/emsdk_env.sh
 
     - name: Configure CMake
       run: cmake -S ${{github.workspace}} -B ${{github.workspace}}/build -DCMAKE_BUILD_TYPE=Release -DCMAKE_INTERPROCEDURAL_OPTIMIZATION=On -DCMAKE_TOOLCHAIN_FILE=emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake