added tests for PinnedPostPage

[guptapriyanshu7]

What kind of change does this PR introduce?

Added test for PinnedPostPage widget

Issue Number:

Fixes #1235

Did you add tests for your changes?

Yes

Have you read the contributing guide?

Yes

[codecov-commenter]

Codecov Report

Merging #1280 (5ef0054) into develop (615b5b6) will increase coverage by 0.51%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #1280      +/-   ##
===========================================
+ Coverage    60.08%   60.59%   +0.51%     
===========================================
  Files          125      125              
  Lines         6363     6360       -3     
===========================================
+ Hits          3823     3854      +31     
+ Misses        2540     2506      -34     

Impacted Files	Coverage Δ
lib/views/pre_auth_screens/set_url.dart	94.49% <0.00%> (-0.06%)	⬇️
lib/main.dart	1.56% <0.00%> (ø)
lib/view_model/lang_view_model.dart	100.00% <0.00%> (ø)
...model/pre_auth_view_models/set_url_view_model.dart	100.00% <0.00%> (ø)
.../pre_auth_screens/waiting_to_join_private_org.dart	100.00% <0.00%> (+1.66%)	⬆️
lib/widgets/custom_list_tile.dart	78.66% <0.00%> (+2.66%)	⬆️
lib/views/pre_auth_screens/change_password.dart	100.00% <0.00%> (+3.22%)	⬆️
lib/widgets/post_widget.dart	88.09% <0.00%> (+3.57%)	⬆️
lib/views/pre_auth_screens/recover.dart	100.00% <0.00%> (+4.16%)	⬆️
lib/models/post/post_model.dart	61.36% <0.00%> (+6.81%)	⬆️
... and 2 more

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[palisadoes]

Do you know why pinned_post_page.dart not showing up in the coverage report?

[guptapriyanshu7]

It could be seen here:
https://app.codecov.io/gh/PalisadoesFoundation/talawa/commit/5ef0054fad38344a3fca7a3c80542e20d9e2a2a2/lib/views/after_auth_screens/feed/pinned_post_page.dart

[palisadoes]

@Sagar2366 @DeltaHarbinger @TheHazeEffect please review.