see also, previous comment in pyproject.toml (removed in this commit).
there is some event loop error happening on app exit with latest flet,
which may or may not be solved with this commit. but since flet is
still essentially in beta phase, seems better to stay on latest
version instead of holding back.
this tries to fix the issue(s) in the following ways:
- timestamp thread is now "daemonized"
- if runtime error happens in timestamp control, ignore and exit thread
- if runtime error happens in main thread error handler, also ignore
we'll see what happens next after some usage
