Fix date display bug (#24047)

Follow
https://github.com/go-gitea/gitea/pull/23988#pullrequestreview-1377696819

Many template helper functions are not good enough and cause various
problems, that's why I am cleaning them.

## Before


![image](https://user-images.githubusercontent.com/51889757/230930898-0c48150f-de85-461d-9455-efcfdc36b644.png)


![image](https://user-images.githubusercontent.com/2114189/231111676-b0da1392-5e47-4f89-a81e-85156aca5cfd.png)


## After


![image](https://user-images.githubusercontent.com/2114189/231111732-920f304d-dd44-4c54-9f5f-518e325006fc.png)

templates/user/dashboard/milestones.tmpl

@@ -93,7 +93,7 @@
 							<div class="meta">
 								{{$closedDate:= TimeSinceUnix .ClosedDateUnix $.locale}}
 								{{if .IsClosed}}
-									{{svg "octicon-clock"}} {{$.locale.Tr "repo.milestones.closed" $closedDate|Str2html}}
+									{{svg "octicon-clock"}} {{$.locale.Tr "repo.milestones.closed" $closedDate | Safe}}
 								{{else}}
 									{{svg "octicon-calendar"}}
 									{{if .DeadlineString}}