Update CHANGELOG, bump version to 0.31

Update CHANGELOG, bump version to 0.30

Merge pull request python-xlib#182 from vasily-v-ryabov/python_39_sup…

…port

Updates for Python 3.9 support

Merge pull request python-xlib#175 from vasily-v-ryabov/prepare_0_28

Prepare 0.28

Merge pull request python-xlib#161 from vasily-v-ryabov/prepare_0_27

Prepare release 0.27

Merge pull request python-xlib#155 from vasily-v-ryabov/prepare_0_26_…

…clean

Prepare 0.26 release

Merge pull request python-xlib#138 from vasily-v-ryabov/prepare_0_25

Bump version in __init__.py

python-xlib 0.24