Bump phoenix from 1.6.15 to 1.7.9 #1717

Job	Run time
Build / Detect Clean Versions	3s
Build / Compile Assets	1m 13s
Dependabot / Automerge PRs	5s
Test / Check Credo	3m 28s
Test / Generate Dialyzer PLT	3m 46s
Docs / Generate	3m 24s
Test / Check Formatting	3m 22s
Test / Sobelow Job	58s
Test / Run Tests & Submit Coverage	5m 23s
Test / Gettext Translations up-to-date	3m 18s
Build / Mix Release	6m 26s
Docs / Upload	0s
Test / Check Dialyzer	0s
Build / Docker Build	0s
	31m 26s

Provide feedback