Fix some issues reported by lintian

See merge request !8

Changes-By: lintian-brush
Fixes: lintian: priority-extra-is-replaced-by-priority-optional
See-also: https://lintian.debian.org/tags/priority-extra-is-replaced-by-priority-optional.html

Changes-By: lintian-brush
Fixes: lintian: uses-debhelper-compat-file
See-also: https://lintian.debian.org/tags/uses-debhelper-compat-file.html

Changes-By: lintian-brush
Fixes: lintian: package-uses-deprecated-debhelper-compat-version
See-also: https://lintian.debian.org/tags/package-uses-deprecated-debhelper-compat-version.html

Changes-By: lintian-brush
Fixes: lintian: maintainer-also-in-uploaders
See-also: https://lintian.debian.org/tags/maintainer-also-in-uploaders.html

Changes-By: lintian-brush
Fixes: lintian: insecure-copyright-format-uri
See-also: https://lintian.debian.org/tags/insecure-copyright-format-uri.html

Changes-By: lintian-brush
Fixes: lintian: trailing-whitespace
See-also: https://lintian.debian.org/tags/trailing-whitespace.html

Update module github.com/olivere/elastic/v7 to v7.0.26

See merge request !7

Update module github.com/olivere/elastic/v7 to v7.0.25

See merge request !6

Update module olivere/elastic/v7 to v7.0.24

See merge request !5

Update module olivere/elastic/v7 to v7.0.23

See merge request !4

Update module olivere/elastic/v7 to v7.0.22

See merge request !3

Configure Renovate

See merge request !2

Update go.mod and vendor

See merge request !1

'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

Also some defaults have been changed.