readme: add emojis to feature overview #1153

Job	Run time
login-shells-and-linting	1m 29s
debug-env	1s
fresh-macos-test (macos-15)	1m 30s
container-test (ubuntu:latest)	1m 17s
fresh-macos-test (macos-14)	1m 30s
runner-test (ubuntu-24.04)	1m 29s
fresh-macos-test (macos-12)	1s
container-test (fedora:latest)	8s
container-test (debian:latest)	1m 18s
runner-test (ubuntu-22.04)	1m 30s
container-test (alpine:latest)	1m 19s
runner-test (macos-15)	1m 31s
container-test (opensuse/leap)	1m 18s
container-test (opensuse/tumbleweed)	1m 18s
runner-test (macos-14)	1m 29s
container-test (kalilinux/kali-rolling)	1m 18s
runner-test (macos-12)	1s
	18m 27s

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