fix indentation when printing double cosets #5875

Job	Run time
Cross compiler for s390x	26m 56s
Test in OpenBSD	7m 44s
testinstall - - ubuntu-latest	4m 26s
teststandard - - ubuntu-latest	19m 40s
testmanuals - - ubuntu-latest	6m 20s
testexpect testmockpkg testspecial test-compile testlibgap testkernel testworkspace - - ubuntu-latest	6m 23s
testpackages testinstall-loadall - - ubuntu-latest	26m 2s
makemanuals testmakeinstall - CONFIGFLAGS="--prefix=/tmp/gapprefix" NO_COVERAGE=1 - ubuntu-latest	6m 34s
teststandard - ABI=32 CONFIGFLAGS="" - ubuntu-20.04	18m 6s
testinstall - HPCGAP=yes ABI=64 - ubuntu-latest	8m 12s
testmockpkg testinstall - BOOTSTRAP_MINIMAL=yes - macos-latest	3m 39s
testbugfix - CONFIGFLAGS="--enable-memory-checking" - ubuntu-latest	28m 58s
testbuildsys testmockpkg testinstall - NO_COVERAGE=1 ABI=64 BUILDDIR=out-of-tree CONFIGFLAGS="--enable-valgrind" - ubuntu-latest	4m 32s
testbuildsys testmockpkg testinstall - NO_COVERAGE=1 ABI=32 BUILDDIR=out-of-tree CONFIGFLAGS="" - ubuntu-20.04	4m 24s
testinstall - JULIA=yes CONFIGFLAGS="--enable-debug" - ubuntu-20.04	4m 36s
testmockpkg testinstall - - windows-2019	15m 52s
Send Slack notification on status change	0s
	3h 12m 24s

Provide feedback