fix: media links in org files not liked to media files

[0Pranav]

In Org files, links to images and videos will be linked to "/media/" path, similar to

gitea/modules/markup/markdown/goldmark.go

Lines 87 to 93 in 6a1a633

	link := v.Destination
	if len(link) > 0 && !markup.IsLink(link) {
	prefix := pc.Get(urlPrefixKey).(string)
	if pc.Get(isWikiKey).(bool) {
	prefix = giteautil.URLJoin(prefix, "wiki", "raw")
	}
	prefix = strings.Replace(prefix, "/src/", "/media/", 1)

Fixes #12831

[codecov-commenter]

Codecov Report

Merging #12997 into master will increase coverage by 0.00%.
The diff coverage is 60.00%.

@@           Coverage Diff           @@
##           master   #12997   +/-   ##
=======================================
  Coverage   42.58%   42.59%           
=======================================
  Files         671      671           
  Lines       73625    73632    +7     
=======================================
+ Hits        31356    31365    +9     
+ Misses      37193    37184    -9     
- Partials     5076     5083    +7     

Impacted Files	Coverage Δ
modules/markup/orgmode/orgmode.go	75.51% <60.00%> (-3.07%)	⬇️
modules/notification/ui/ui.go	80.55% <0.00%> (-2.78%)	⬇️
services/pull/check.go	47.69% <0.00%> (-2.31%)	⬇️
models/notification.go	65.76% <0.00%> (-0.91%)	⬇️
models/error.go	34.85% <0.00%> (-0.34%)	⬇️
modules/notification/mail/mail.go	34.48% <0.00%> (ø)
modules/git/repo.go	46.70% <0.00%> (+0.50%)	⬆️
services/mailer/mail.go	55.91% <0.00%> (+1.07%)	⬆️
models/unit.go	49.31% <0.00%> (+2.73%)	⬆️
modules/git/utils.go	77.04% <0.00%> (+3.27%)	⬆️
... and 3 more

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[zeripath]

Thanks for the PR - this looks like it would solve the problem - however, as a r is an io.Writer we should just get fmt.Fprintf to write to it directly instead of using the r.WriteString method.