File use-python-3.6.patch of Package piper

--- a/meson.build
+++ b/meson.build
@@ -78,7 +78,7 @@ subdir('po')
 
 # Find the directory to install our Python code
 pymod = import('python')
-py3 = pymod.find_installation(modules: python_modules)
+py3 = pymod.find_installation('python3.6', modules: python_modules)
 python_dir = py3.get_install_dir()
 install_subdir('piper',
                install_dir: python_dir,