Fix escaping issue in diff

[zeripath]

Ensure that linecontent is escaped before passing to template.HTML

Signed-off-by: Andrew Thornton art27@cantab.net

[codecov-io]

Codecov Report

Merging #14153 (35b5885) into master (a19447a) will decrease coverage by 0.06%.
The diff coverage is 39.72%.

@@            Coverage Diff             @@
##           master   #14153      +/-   ##
==========================================
- Coverage   42.36%   42.29%   -0.07%     
==========================================
  Files         727      727              
  Lines       77931    77999      +68     
==========================================
- Hits        33013    32990      -23     
- Misses      39513    39605      +92     
+ Partials     5405     5404       -1     

Impacted Files	Coverage Δ
routers/user/setting/keys.go	11.11% <13.33%> (+0.31%)	⬆️
routers/api/v1/user/key.go	53.39% <28.57%> (-1.25%)	⬇️
models/ssh_key.go	46.47% <48.97%> (+0.17%)	⬆️
services/gitdiff/gitdiff.go	68.99% <50.00%> (-2.00%)	⬇️
models/unit_tests.go	41.28% <0.00%> (-33.03%)	⬇️
models/project.go	18.30% <0.00%> (-28.17%)	⬇️
models/unit.go	41.09% <0.00%> (-5.48%)	⬇️
modules/charset/charset.go	73.03% <0.00%> (-2.25%)	⬇️
modules/queue/unique_queue_disk_channel.go	53.84% <0.00%> (-1.54%)	⬇️
... and 6 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 5a1ccac...35b5885. Read the comment docs.