feat: watch work forever if timeout is not specified

[tomplus]

Related to: #29

[codecov-io]

Codecov Report

Merging #30 into master will decrease coverage by 0.35%.
The diff coverage is 84.37%.

@@            Coverage Diff             @@
##           master      #30      +/-   ##
==========================================
- Coverage   93.48%   93.13%   -0.36%     
==========================================
  Files          16       16              
  Lines         967      990      +23     
==========================================
+ Hits          904      922      +18     
- Misses         63       68       +5

Impacted Files	Coverage Δ
kubernetes_asyncio/watch/watch_test.py	96.25% <100%> (+0.47%)	⬆️
kubernetes_asyncio/watch/watch.py	87.67% <78.26%> (-5.55%)	⬇️

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