fix(module:date-picker): added missing type attributes for buttons

[slavafomin]

This should fix #7012

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix

What is the current behavior?

Issue Number: #7012

What is the new behavior?

Buttons are not submitting the form anymore.

Does this PR introduce a breaking change?

[ ] Yes
[ ] No
[x] Don't think so

Other information

[zorro-bot]

This preview will be available after the AzureCI is passed.

[codecov]

Codecov Report

Merging #7013 (aa61692) into master (9a3f569) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7013      +/-   ##
==========================================
- Coverage   89.52%   89.48%   -0.04%     
==========================================
  Files         489      489              
  Lines       15802    15752      -50     
  Branches     2572     2572              
==========================================
- Hits        14147    14096      -51     
+ Misses       1015     1013       -2     
- Partials      640      643       +3     

Impacted Files	Coverage Δ
components/result/result.component.ts	89.65% <0.00%> (-3.45%)	⬇️
components/pipes/nz-aggregate.pipe.ts	66.66% <0.00%> (-2.57%)	⬇️
components/pipes/nz-sanitizer.pipe.ts	77.77% <0.00%> (-2.23%)	⬇️
components/tree/tree-drop-indicator.component.ts	58.33% <0.00%> (-1.67%)	⬇️
components/tabs/tab-nav-bar.component.ts	81.56% <0.00%> (-1.48%)	⬇️
components/time-picker/time-holder.ts	94.73% <0.00%> (-1.06%)	⬇️
components/form/form-label.component.ts	83.87% <0.00%> (-0.51%)	⬇️
components/core/util/convert.ts	85.71% <0.00%> (-0.50%)	⬇️
components/slider/slider.component.ts	90.03% <0.00%> (-0.48%)	⬇️
components/core/time/candy-date.ts	86.48% <0.00%> (-0.27%)	⬇️
... and 30 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 9a3f569...aa61692. Read the comment docs.

[wenqi73]

@slavafomin Thanks!

[slavafomin]

@wenqi73 no problem. When is it going to be released? This issue is seriously affecting our products.