Update sbt-git to 0.6.4

[scala-steward]

Updates com.typesafe.sbt:sbt-git from 0.6.2 to 0.6.4.

I'll automatically update this PR to resolve conflicts as long as you don't change it yourself.

If you'd like to skip this version, you can just close this PR. If you have any feedback, just mention @scala-steward in the comments below.

Have a nice day!

[SethTisue]

https://github.com/sbt/sbt-git/releases

not sure why scala-steward didn't choose a later version like 0.9.3 or 1.0? but okay

[fthomas]

The bot is conservative. If there is a version with the same minor version number but a greater patch version number it creates a PR for this version first even if a newer version with a greater minor version number exists. The rationale for this strategy is that bumps of patch version numbers are more likely to be merged because they require less human intervention.

[SethTisue]

interesting, thanks for the insight.