Add solution for Challenge 6 by mick4711 #25

Job	Run time
Validate Submission Security	5s
test-submissions (challenge-4)	13s
test-submissions (challenge-2)	26s
test-submissions (challenge-3)	24s
test-submissions (challenge-7)	12s
test-submissions (challenge-10)	13s
test-submissions (challenge-6)	21s
test-submissions (challenge-9)	15s
test-submissions (challenge-5)	14s
test-submissions (challenge-11)	13s
test-submissions (challenge-13)	13s
test-submissions (challenge-15)	10s
test-submissions (challenge-8)	16s
test-submissions (challenge-1)	17s
test-submissions (challenge-14)	11s
test-submissions (challenge-17)	14s
test-submissions (challenge-16)	15s
test-submissions (challenge-20)	12s
test-submissions (challenge-18)	8s
test-submissions (challenge-19)	9s
test-submissions (challenge-12)	23s
test-submissions (challenge-21)	13s
test-submissions (challenge-23)	12s
test-submissions (challenge-22)	8s
test-submissions (challenge-26)	6s
test-submissions (challenge-25)	12s
test-submissions (challenge-27)	15s
test-submissions (challenge-29)	14s
test-submissions (challenge-28)	19s
test-submissions (challenge-30)	11s
test-submissions (challenge-24)	14s
	7m 8s

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