update the workflow

Author: mili1247

.github/workflows/build.yml

@@ -64,7 +64,7 @@ jobs:
     - name: Install homebrew dependencies
       if: matrix.os == 'macos-12'
       run: |
-        brew install gcc@11 llvm boost fftw hdf5 open-mpi openblas
+        brew install python3 gcc@11 llvm boost fftw hdf5 open-mpi openblas
         brew install wentzell/triqs/nfft
         pip3 install mako numpy scipy mpi4py
         pip3 install -r requirements.txt
@@ -81,7 +81,7 @@ jobs:
       run: |
         git clone https://github.com/TRIQS/triqs --branch unstable
         mkdir triqs/build && cd triqs/build
-        cmake .. -DBuild_Tests=OFF -DCMAKE_INSTALL_PREFIX=$HOME/install
+        cmake .. -DBuild_Tests=OFF -DCMAKE_INSTALL_PREFIX=$HOME/install -DPYTHON_EXECUTABLE=$(which python3)
         make -j1 install VERBOSE=1
         cd ../