Merge branch 'pip_macos' into 'master'

Use pip on macOS from the source tarball

See merge request lfortran/lfortran!213

ci/azure_install_macos.sh

@@ -6,6 +6,7 @@ conda config --set always_yes yes --set changeps1 no
 conda info -a
 conda update -q conda
 conda install python=3.7 pytest llvmlite prompt_toolkit cmake make
+conda install -c conda-forge scikit-build
 pip install antlr4-python3-runtime
 
 python grammar/asdl_py.py
@@ -16,7 +17,11 @@ curl -O https://www.antlr.org/download/antlr-4.7-complete.jar
 java -cp antlr-4.7-complete.jar org.antlr.v4.Tool -Dlanguage=Python3 -no-listener -visitor fortran.g4 -o ../lfortran/parser
 cd ..
 
-cmake -DCMAKE_INSTALL_PREFIX=`pwd` .
-cmake --build . --target install
+ci/version.sh
+lfortran_version=$(<version)
 
-pytest
+python setup.py sdist
+tar xzf dist/lfortran-${lfortran_version}.tar.gz
+cd lfortran-${lfortran_version}
+pip install -v .
+py.test --pyargs lfortran