Allow erlang/otp release to trigger images' build flow #311

Job	Run time
docker (DIR=master)	17m 7s
docker (DIR=master VARIANT=alpine)	10m 37s
docker (DIR=26)	12m 59s
docker (DIR=26 VARIANT=slim)	10m 50s
docker (DIR=26 VARIANT=alpine)	11m 53s
docker (DIR=25)	20m 17s
docker (DIR=25 VARIANT=slim)	13m 18s
docker (DIR=25 VARIANT=alpine)	11m 23s
docker (DIR=24)	15m 4s
docker (DIR=24 VARIANT=slim)	10m 44s
docker (DIR=24 VARIANT=alpine)	14m 24s
docker (DIR=23)	16m 16s
docker (DIR=23 VARIANT=slim)	11m 32s
docker (DIR=23 VARIANT=alpine)	10m 7s
docker (DIR=22)	19m 39s
docker (DIR=22 VARIANT=slim)	15m 46s
docker (DIR=22 VARIANT=alpine)	15m 47s
docker (DIR=21)	16m 50s
docker (DIR=21 VARIANT=slim)	17m 7s
docker (DIR=20)	21m 33s
docker (DIR=20 VARIANT=slim)	17m 4s
	5h 10m 17s

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