Bump elliptic from 6.5.3 to 6.5.7 in /test/dockerfiles/webpack #656

Job	Run time
prepare (mainline)	24s
prepare (buildkit)	9s
prepare (desktop)	25s
validate (./hack/lint)	32s
e2e (mainline, pip-youtube-dl, linux/arm/v7)	1m 18s
validate (./hack/validate-vendor)	20s
test (mainline)	3m 38s
e2e (mainline, webpack, linux/arm/v7)	1m 57s
validate (./hack/install-and-test)	48s
test (buildkit)	35s
e2e (desktop, pip-youtube-dl, linux/arm/v7)	1m 20s
test (desktop)	7s
e2e (desktop, webpack, linux/arm/v7)	2m 21s
e2e (mainline, ejabberd, linux/arm64)	14m 18s
e2e (desktop, tini, linux/arm64, --rm)	38s
e2e (desktop, postgis, linux/arm64, -d --name postgis, postgis, UTC [1] LOG: database system is ...	44s
build (mainline)	33m 26s
build (buildkit)	31m 44s
build (desktop)	33m 34s
	2h 8m 18s

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