downgrade to ubuntu-16.04

update to elgohr/Publish-Docker-Github-Action@2.6

Merge pull request imgbot#495 from ElSiipo/master

add support for mozJpeg compression

Merge pull request imgbot#489 from dabutvin/check-size

make sure fileAfter size is greater than 0 before adding

Merge pull request imgbot#482 from dabutvin/dependabot/nuget/Magick.N…

…ET-Q16-AnyCPU-7.14.4

Bump Magick.NET-Q16-AnyCPU from 7.14.1 to 7.14.4

Merge pull request imgbot#443 from dabutvin/dependabot/nuget/Magick.N…

…ET-Q16-AnyCPU-7.14.1

Bump Magick.NET-Q16-AnyCPU from 7.14.0.2 to 7.14.1

Merge pull request imgbot#322 from dabutvin/dependabot/nuget/LibGit2S…

…harp-0.26.0

Bump LibGit2Sharp from 0.25.4 to 0.26.0

Bump Magick.NET-Q16-AnyCPU from 7.14.0.1 to 7.14.0.2

Bumps [Magick.NET-Q16-AnyCPU](https://github.com/dlemstra/Magick.NET) from 7.14.0.1 to 7.14.0.2.
- [Release notes](https://github.com/dlemstra/Magick.NET/releases)
- [Commits](dlemstra/Magick.NET@7.14.0.1...7.14.0.2)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Merge pull request imgbot#416 from dabutvin/cleanup

clean up local temp directory proactively

Merge pull request imgbot#393 from dabutvin/timeout

bump up timeout even further