Add DLR training events for the first half year of 2021

10 jobs for master in 7 minutes (queued for 3 seconds)
Status Job ID Name Coverage
  Build
passed #237409
build:latest

00:01:58

passed #237414
build:production

00:01:09

passed #237413
build:production:review-apps

00:00:56

passed #237411
build:production:subpath

00:01:19

 
  Test
passed #237416
test:htmlproofer

00:01:44

failed #237721
internal
test:htmlproofer:external_links

00:02:30

passed #237418
test:htmlproofer:subpath

00:01:47

failed #237419
internal
test:htmlproofer:external_links

00:02:38

 
  Review
skipped #237422
review-apps allowed to fail manual
stop_review
 
  Deploy
skipped #237423
internal
production
 
Name Stage Failure
failed
test:htmlproofer:external_links Test
- ./_site/events/2019/06/04/deRSE19.html
* External link https://derse19.uni-jena.de/derse19/cfp failed: response code 0 means something's wrong.
It's possible libcurl couldn't connect to the server or perhaps the request timed out.
Sometimes, making too many requests at once also breaks things.
Either way, the return message (if any) from the server is: SSL peer certificate or SSH remote key was not OK

HTML-Proofer found 1 failure!
Cleaning up file based variables
ERROR: Job failed: exit code 1