Fix PlantUML integration in GFM

What does this MR do?

Use "lang" attribute instead of "class" in PlantumlFilter.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• [ ] Documentation created/updated
• [ ] API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Fixes #30557 (closed)

marked the task Changelog entry added, if necessary as completed

added 1 commit

• aabe95c3 - Move PlantumlFilter after SyntaxHighlightFilter in GfmPipeline

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assigned to @jarka

@jarka can you review?

changed milestone to %9.1

added ~149423 label

assigned to @adamniedzielski

@jarka Thanks for reviewing. I added the comment and I'm passing to @DouweM.

assigned to @DouweM

added 90 commits

• aabe95c3...9daf4f64 - 89 commits from branch master
• b7253d4d - Move PlantumlFilter after SyntaxHighlightFilter in GfmPipeline

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resolved all discussions

In my environment it has been correctly rendered by your modifications. Thanks!

• GitLab-ce 9.0.5
• Tomcat7 + PlantUML Server 20170413-0753 / version 201709

assigned to @rspeicher

@adamniedzielski Couple questions.

assigned to @adamniedzielski

added 1 commit

• 8edcdcea - Fix PlantUML integration in GFM

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changed title from Move PlantumlFilter after SyntaxHighlightFilter in GfmPipeline to Fix PlantUML integration in GFM

assigned to @rspeicher

I think this should also go in 9.0 so once picked into 9.1 we'll have to update the milestone. /cc @godfat @felipe_artur @twk3

added regression label

mentioned in issue #31059 (closed)

assigned to @adamniedzielski

resolved all discussions

added 252 commits

• 8edcdcea...a9446a27 - 251 commits from branch master
• 0945dc41 - Fix PlantUML integration in GFM

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assigned to @smcgivern

approved this merge request

enabled an automatic merge when the pipeline for 0945dc41 succeeds

merged

mentioned in commit 08b2e7cd

Picked into 9-1-stable, will go into 9.1.0-rc6

changed milestone to %9.0

mentioned in commit d9a407d1

Picked into stable. Will be in 9.0.6.

mentioned in commit bd2c22d6

As always with you guys, I'm very impressed with your responsiveness!!