3.2.0

• ⚠️ removed support for Python 3.4
• MSS: add the Screenshot.bgra attribute
• MSS: speed-up grabbing on the 3 platforms
• tools: add PNG compression level control to to_png()
• tests: add leaks.py and benchmarks.py for manual testing
• doc: add an example about capturing part of the monitor 2
• doc: add an example about computing BGRA values to RGB