fix: Bump Go to 1.19

[danez]

Summary

What I noticed is that we install the latest patch version with 1.19.x but then always use and also freeze (in bitballoon) 1.19 version. So we never actually use the latest patch version. Should we also freeze and use 1.19.x by default? That though would mean that new sites that have 1.19.x frozen will automatically get patch updates installed.

If we freeze 1.19 we should also install 1.19 and not the latest patch version of 1.19.x

Ref: netlify/bitballoon#13837

Fixes: https://github.com/netlify/pod-compute/issues/188

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[danez]

Updated to use 1.19.x as default version