chore: modify appveyor build

Author: sriram-mv

.appveyor.yml

@@ -15,15 +15,16 @@ build: off
 install:
 # To run Nodejs workflow integ tests
 - ps: Install-Product node 8.10
-
-- "set PATH=%PYTHON%\\Scripts;%PYTHON%\\bin;%PATH%"
-- "%PYTHON%\\python.exe -m pip install -r requirements/dev.txt"
-- "%PYTHON%\\python.exe -m pip install -e ."
-- "python --version"
-- "set PATH=C:\\Ruby25-x64\\bin;%PATH%"
-- "gem install bundler --no-ri --no-rdoc"
-- "bundler --version"
+- ps: $env:Path = "$env:PYTHON;$env:Path"
+- ps: python --version
+- ps: python -m pip install -r requirements/dev.txt
+- ps: python -m pip install -e .
+- ps: python --version
+- ps: $env:Path = "C:\\Ruby25-x64\\bin;$env:Path"
+- ps: ruby --version
+- ps: gem install bundler --no-ri --no-rdoc
+- ps: bundler --version
 
 test_script:
-- "%PYTHON%\\python.exe -m pytest --cov aws_lambda_builders --cov-report term-missing tests/unit tests/functional"
-- "%PYTHON%\\python.exe -m pytest tests/integration"
+- ps: python -m pytest --cov aws_lambda_builders --cov-report term-missing tests/unit tests/functional
+- ps: python -m pytest tests/integration