Use libtmux w/ dataclasses branch

[tony]

See tmux-python/libtmux#426

[codecov]

Codecov Report

Merging #850 (eea18d2) into master (cf784c0) will decrease coverage by 0.44%.
The diff coverage is 69.81%.

❗ Current head eea18d2 differs from pull request most recent head 36e99bc. Consider uploading reports for the commit 36e99bc to get more accurate results

@@            Coverage Diff             @@
##           master     #850      +/-   ##
==========================================
- Coverage   72.24%   71.79%   -0.45%     
==========================================
  Files          25       25              
  Lines        1758     1769      +11     
  Branches      393      396       +3     
==========================================
  Hits         1270     1270              
- Misses        378      388      +10     
- Partials      110      111       +1     

Impacted Files	Coverage Δ
src/tmuxp/workspace/builder.py	86.13% <41.66%> (-2.19%)	⬇️
src/tmuxp/cli/freeze.py	71.57% <50.00%> (ø)
src/tmuxp/util.py	78.31% <74.19%> (-6.11%)	⬇️
src/tmuxp/cli/shell.py	85.45% <100.00%> (ø)
src/tmuxp/workspace/freezer.py	82.50% <100.00%> (ø)

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more