Bump ex_doc from 0.30.7 to 0.30.8 #792

Job	Run time
Docs / Generate	2m 25s
Test / Check Credo	2m 26s
Test / Run Tests & Submit Coverage	3m 10s
Test / Generate Dialyzer PLT	3m 28s
Test / Check Formatting	3m 49s
Test / Gettext Translations up-to-date	2m 48s
Test / Sobelow Job	49s
Build / Compile Assets	55s
Build / Detect Clean Versions	6s
Dependabot / Automerge PRs	9s
Build / Mix Release	1m 15s
Build / Docker Build	0s
Docs / Upload	0s
Test / Check Dialyzer	2m 30s
	23m 50s

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