Update dependency svgicons2svgfont to v15 #96156

Job	Run time
Determine tests matrix	1m 17s
E2E: Build jetpack-boost	3m 18s
E2E: Build jetpack-core	4m 10s
E2E: Build jetpack-search	4m 6s
E2E: Build jetpack-social	3m 47s
E2E: Build jetpack-sync	4m 14s
E2E: Build jetpack-videopress	3m 6s
Jetpack connection e2e tests	3m 57s
Jetpack pre-connection e2e tests	2m 38s
Jetpack post-connection e2e tests	4m 44s
Jetpack post editor e2e tests	3m 53s
Jetpack sync e2e tests	3m 53s
Jetpack Boost - Base e2e tests	4m 10s
Jetpack Boost - Modules e2e tests	3m 45s
Jetpack Boost - Critical CSS e2e tests	3m 43s
Jetpack Boost - Page Cache e2e tests	3m 21s
Jetpack Boost - Concatenate JS and CSS e2e tests	3m 32s
Jetpack Boost - Image CDN e2e tests	2m 53s
Jetpack Boost - Image Guide e2e tests	2m 33s
Search e2e tests	4m 17s
VideoPress e2e tests	2m 31s
Social e2e tests	5m 5s
Test report	1s
Slack notification	54s
	1h 19m 48s

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