Merge pull request #39 from Textualize/colors-and-borders-demo-updates

Fixes and updates in demo apps for new themes

fix for screenshots

bump

Merge pull request #29 from Textualize/lazy

lazy windgets

Merge pull request #28 from Textualize/fix-textual-command-not-working

Fix `textual` CLI not working, drop Python 3.7.