fix(datepicker): add missing show header input

[yggg]

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• I read and followed the CONTRIBUTING.md guide.
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Short description of what this resolves:

Closes #1833

[codecov]

Codecov Report

Merging #1889 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1889      +/-   ##
==========================================
+ Coverage   84.07%   84.07%   +<.01%     
==========================================
  Files         234      234              
  Lines        7724     7726       +2     
  Branches      680      680              
==========================================
+ Hits         6494     6496       +2     
  Misses       1032     1032              
  Partials      198      198

Impacted Files	Coverage Δ
...heme/components/datepicker/datepicker.component.ts	90.21% <100%> (+0.1%)	⬆️