fix(DatePicker): defaultDate should consider maxDate & minDate

[paranoidjk]

fix #1033

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[mention-bot]

@paranoidjk, thanks for your PR! By analyzing the history of the files in this pull request, we identified @yiminghe, @ottomao and @warmhug to be potential reviewers.

[codecov]

Codecov Report

Merging #1035 into master will increase coverage by 0.01%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##           master    #1035      +/-   ##
==========================================
+ Coverage   69.13%   69.14%   +0.01%     
==========================================
  Files         215      215              
  Lines        3936     3947      +11     
  Branches     1177     1181       +4     
==========================================
+ Hits         2721     2729       +8     
- Misses       1213     1216       +3     
  Partials        2        2

Flag	Coverage Δ
#rn	73.16% <80%> (+0.04%)	⬆️
#web	64.98% <100%> (-0.06%)	⬇️

Impacted Files	Coverage Δ
components/date-picker/index.tsx	92.85% <100%> (-3.58%)	⬇️
components/date-picker/index.web.tsx	92.59% <100%> (-3.71%)	⬇️
components/date-picker/utils.tsx	84.61% <77.77%> (+4.61%)	⬆️
components/slider/index.tsx	85.71% <0%> (+3.89%)	⬆️

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