[minor] use of deprecated default settings for goreleaser

[splashx]

When building the following messages are seen

$ goreleaser --skip-publish --rm-dist  --skip-validate

   • releasing using goreleaser 0.97.0...
   • loading config file       file=goreleaser.yml
   • RUNNING BEFORE HOOKS
   • GETTING AND VALIDATING GIT STATE
      • releasing v1.3.1, commit 0935d402b755efdae0d06595b9f183b84d5bbb63
      • skipped                   reason=validation is disabled
   • SETTING DEFAULTS
+         • DEPRECATED: `docker.image` should not be used anymore, check https://goreleaser.com/deprecations#docker-image for more info.
+         • DEPRECATED: `docker.tag_templates` should not be used anymore, check https://goreleaser.com/deprecations#docker-tag-templates for more info.
+         • DEPRECATED: `docker.binary` should not be used anymore, check https://goreleaser.com/deprecations#docker-binary for more info.
+         • DEPRECATED: `docker.image` should not be used anymore, check https://goreleaser.com/deprecations#docker-image for more info.
+         • DEPRECATED: `docker.tag_templates` should not be used anymore, check https://goreleaser.com/deprecations#docker-tag-templates for more info.
+         • DEPRECATED: `docker.binary` should not be used anymore, check https://goreleaser.com/deprecations#docker-binary for more info.
   • SNAPSHOTING
      • skipped                   reason=not a snapshot
   • CHECKING ./DIST
      • --rm-dist is set, cleaning it up
   • WRITING EFFECTIVE CONFIG FILE
      • writing                   config=dist/config.yaml
   • GENERATING CHANGELOG
      • writing                   changelog=dist/CHANGELOG.md
   • LOADING ENVIRONMENT VARIABLES
      • skipped                   reason=publishing is disabled
   • BUILDING BINARIES
      • building                  binary=dist/linux_amd64/n2proxy
      • building                  binary=dist/linux_arm_6/n2proxy
      • building                  binary=dist/darwin_amd64/n2proxy
   • ARCHIVES
      • creating                  archive=dist/n2proxy_macOS_amd64.tar.gz
      • creating                  archive=dist/n2proxy_linux_amd64.tar.gz
      • creating                  archive=dist/n2proxy_linux_arm.tar.gz
   • LINUX PACKAGES WITH NFPM
      • creating                  file=dist/n2proxy_amd64.deb package=n2proxy_amd64.deb
      • creating                  file=dist/n2proxy_amd64.rpm package=n2proxy_amd64.rpm
      • creating                  file=dist/n2proxy_armv6.rpm package=n2proxy_armv6.rpm
      • creating                  file=dist/n2proxy_armv6.deb package=n2proxy_armv6.deb
   • SNAPCRAFT PACKAGES
      • ignored unsupported arch  arch=armel
      • creating                  arch=amd64 snap=dist/n2proxy_amd64.snap
   • CALCULATING CHECKSUMS
      • checksumming              file=n2proxy_amd64.rpm
      • checksumming              file=n2proxy_macOS_amd64.tar.gz
      • checksumming              file=n2proxy_amd64.deb
      • checksumming              file=n2proxy_linux_arm.tar.gz
      • checksumming              file=n2proxy_linux_amd64.tar.gz
      • checksumming              file=n2proxy_armv6.rpm
      • checksumming              file=n2proxy_armv6.deb
   • SIGNING ARTIFACTS
      • skipped                   reason=artifact signing is disabled
   • DOCKER IMAGES
      • building docker image     image=txn2/n2proxy:armhf-1.3.1
      • building docker image     image=txn2/n2proxy:1.3.1
   • PUBLISHING
      • skipped                   reason=publishing is disabled
   • release succeeded after 6.65s

[cjimti]

Thanks @splashx