Update setup.py

Fixes python-poetry/poetry#3140

Author: sobolevn

Diff for: python/setup.py

@@ -12,10 +12,7 @@
     history = history_file.read()
 
 requirements = [
-    # wasmer, if we are in Linux x86_64
-    'wasmer>=0.3.0; python_version>="3.5" and platform_machine=="x86_64" and sys_platform=="linux"',
-    # wasmer, if we are in macOS x86_64
-    'wasmer>=0.3.0; python_version>="3.5" and platform_machine=="x86_64" and sys_platform=="darwin"'
+    'wasmer>=0.3.0; python_version>="3.5" and platform_machine=="x86_64" and (sys_platform=="linux" or sys_platform=="darwin")',
 ]
 
 setup_requirements = ['pytest-runner', ]