Update go.mod and vendor
go build .
yields this error otherwise:
$ go build .
go: inconsistent vendoring in /tmp/logcat:
github.com/olivere/elastic/v7@v7.0.19: is explicitly required in go.mod, but not marked as explicit in vendor/modules.txt
run 'go mod vendor' to sync, or use -mod=mod or -mod=readonly to ignore the vendor directory