add replies_count parameter in Status

[moko256]

Since Mastodon v2.5.0rc1, Statuses have count of replies. This pull request enable to get it.

[codecov-io]

Codecov Report

Merging #68 into master will decrease coverage by 0.06%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master      #68      +/-   ##
============================================
- Coverage     54.25%   54.18%   -0.07%     
  Complexity      147      147              
============================================
  Files            44       44              
  Lines           800      801       +1     
  Branches         80       80              
============================================
  Hits            434      434              
- Misses          352      353       +1     
  Partials         14       14

Impacted Files	Coverage Δ	Complexity Δ
.../java/com/sys1yagi/mastodon4j/api/entity/Status.kt	39.28% <0%> (-1.46%)	6 <0> (ø)

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