Upgrade sbt to 1.3.6

The crosbuild issue is fixed now (https://github.com/sbt/sbt/issues/5336),
this is related to 3cdf9d6f

Signed-off-by: 35V LG84 <35vlg84-x4e6b92@e257.fi>
3 jobs for spring-boot-example in 10 minutes and 24 seconds
latest
Status Job ID Name Coverage
  Test
passed #457170233
codecov

00:07:56

99.8%
passed #457170231
test·jdk11

00:01:24

passed #457170232
test·jdk8

00:10:24