Update llvm paths for Apple silicon homebrew paths

Signed-off-by: Dan Bailey <danbailey@ilm.com>

.github/workflows/houdini.yml

@@ -162,7 +162,7 @@ jobs:
         cp hou/hou.tar.gz $HOME/houdini_install/hou.tar.gz
         cd $HOME/houdini_install && tar -xzf hou.tar.gz && cd -
     - name: install_deps
-      run: ./ci/install_macos.sh ${{ matrix.config.llvm }}
+      run: ./ci/install_macos.sh 15
     - name: build
       run: |
         ./ci/build.sh -v \
@@ -175,7 +175,7 @@ jobs:
             -DDISABLE_CMAKE_SEARCH_PATHS=ON \
             -DDISABLE_DEPENDENCY_VERSION_CHECKS=ON \
             -DUSE_EXPLICIT_INSTANTIATION=OFF \
-            -DLLVM_DIR=/usr/local/opt/llvm@15/lib/cmake/llvm \
+            -DLLVM_DIR=/opt/homebrew/opt/llvm@15/lib/cmake/llvm \
             -DCMAKE_INSTALL_PREFIX=${{ github.workspace }}/install \
             \"
     - name: test