chore: use -coverpkg for extended code coverage reports #829

Job	Run time
build (1.20.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	13s
build (1.20.x, amd64, linux, ./pkg/amino/cmd/goscan)	14s
test (1.20.x, _test.flappy)	37s
build (1.20.x, amd64, linux, ./pkg/autofile/cmd)	12s
test (1.20.x, _test.pkg.amino)	3m 59s
build (1.20.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	19s
test (1.20.x, _test.pkg.bft)	5m 37s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/aminoscan)	19s
test (1.20.x, _test.pkg.others)	5m 55s
build (1.21.x, amd64, linux, ./pkg/amino/cmd/goscan)	13s
test (1.21.x, _test.flappy)	43s
build (1.21.x, amd64, linux, ./pkg/autofile/cmd)	11s
test (1.21.x, _test.pkg.amino)	5m 9s
build (1.21.x, amd64, linux, ./pkg/iavl/cmd/iaviewer)	18s
test (1.21.x, _test.pkg.bft)	5m 4s
test (1.21.x, _test.pkg.others)	6m 1s
upload-coverage	12s
	35m 16s

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