fix(module:date-picker): not switch month panel when range is same month

[wenqi73]

fix #6322 (comment)

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
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[ ] No

Other information

[codecov]

Codecov Report

Merging #6616 (a1f11bd) into master (62e4bb6) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head a1f11bd differs from pull request most recent head 628badd. Consider uploading reports for the commit 628badd to get more accurate results

@@           Coverage Diff           @@
##           master    #6616   +/-   ##
=======================================
  Coverage   89.93%   89.94%           
=======================================
  Files         481      481           
  Lines       15379    15381    +2     
  Branches     2344     2345    +1     
=======================================
+ Hits        13831    13834    +3     
+ Misses        931      930    -1     
  Partials      617      617           

Impacted Files	Coverage Δ
components/typography/text-copy.component.ts	94.73% <ø> (ø)
components/core/time/candy-date.ts	86.75% <100.00%> (+0.17%)	⬆️
components/time-picker/time-holder.ts	94.73% <0.00%> (-1.06%)	⬇️
components/core/util/text-measure.ts	91.30% <0.00%> (+1.73%)	⬆️

---

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 62e4bb6...628badd. Read the comment docs.