Release v1.3.0

• Add examples.work_together_with_other_asgi_app.py, thanks @davidbrochart
• LDAP is now optional
• uvicorn is now optional
• FileSystemProvider uses more aiofiles API
• Change DAVRequest.depth's default value from DAVDepth.infinity to DAVDepth.d0
• PROPFIND will return 200 if only one DAV property response in the return