starters: update GH workflow due to GH action deprecation #401

Job	Run time
packages_split (starters/academic-cv, theme-academic-cv)	12s
packages_split (starters/resume, theme-resume)	7s
packages_split (starters-bootstrap/markdown-slides, theme-markdown-slides)	9s
packages_split (starters/blog, theme-blog)	9s
packages_split (starters/documentation, theme-documentation)	9s
packages_split (starters-bootstrap/portfolio, theme-portfolio)	9s
packages_split (starters-bootstrap/course, theme-online-course)	7s
packages_split (starters/link-in-bio, theme-link-in-bio)	8s
packages_split (starters-bootstrap/research-group, theme-research-group)	8s
packages_split (starters-bootstrap/second-brain, theme-second-brain)	10s
packages_split (starters/landing-page, theme-landing-page)	9s
	1m 37s

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