Bump codecov/codecov-action from 3 to 4 #616

Job	Run time
Documentation	4m 50s
Julia 1.6 - ubuntu-latest - x64 - pull_request	3m 12s
Julia 1.6 - macOS-latest - x64 - pull_request	5m 54s
Julia 1.6 - windows-latest - x64 - pull_request	9m 5s
Julia 1 - ubuntu-latest - x64 - pull_request	3m 26s
Julia 1 - macOS-latest - x64 - pull_request	4m 39s
Julia 1 - windows-latest - x64 - pull_request	8m 56s
Julia nightly - ubuntu-latest - x64 - pull_request	4m 38s
Julia nightly - macOS-latest - x64 - pull_request	8m 51s
Julia nightly - windows-latest - x64 - pull_request	7m 26s
	1h 0m 57s

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