style(.DiagramGR): add missing whitespaces

3 jobs for dev in 5 minutes and 18 seconds (queued for 3 seconds)
Status Name Job ID Coverage
  Check
passed check_as_cran_devel #188670

00:01:46

passed check_as_cran_oldrel #188671

00:01:37

passed check_as_cran_patched #188669

00:01:54