Merge remote-tracking branch 'origin/bitfireAT/master'

# Conflicts:
#	.gitlab-ci.yml
#	build.gradle
#	src/androidTest/java/foundation/e/ical4android/AndroidCalendarTest.kt
#	src/androidTest/java/foundation/e/ical4android/AndroidEventTest.kt
#	src/androidTest/java/foundation/e/ical4android/AndroidTaskListTest.kt
#	src/androidTest/java/foundation/e/ical4android/AndroidTaskTest.kt
#	src/main/java/at/bitfire/ical4android/EventColor.kt
#	src/main/java/foundation/e/ical4android/Css3Color.kt
#	src/main/java/foundation/e/ical4android/EventColor.kt
#	src/main/java/foundation/e/ical4android/ICalendar.kt
#	src/test/java/at/bitfire/ical4android/EventColorTest.kt
#	src/test/java/foundation/e/ical4android/Css3ColorTest.kt
#	src/test/java/foundation/e/ical4android/EventColorTest.kt