Bump bufbuild/buf-setup-action from 1.38.0 to 1.39.0 #739

Job	Run time
build-library-macos	2m 41s
build-eliza-cocoapods-example	1m 28s
build-eliza-swiftpm-example	2m 33s
build-library-ios	3m 35s
build-library-watchos	3m 9s
build-plugin-and-generate	1m 4s
build-library-tvos	3m 15s
run-conformance-tests	2m 38s
run-swiftlint	13s
run-unit-tests	1m 47s
validate-license-headers	18s
	22m 41s

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