Update sbt-header to 5.4.0

[scala-steward]

Updates de.heikoseeberger:sbt-header from 5.3.1 to 5.4.0.

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 me in the comments below.

Have a fantastic day writing Scala!

Ignore future updates

Add this to your .scala-steward.conf file to ignore future updates of this dependency:

updates.ignore = [ { groupId = "de.heikoseeberger", artifactId = "sbt-header" } ]

labels: sbt-plugin-update, semver-minor

[codecov-io]

Codecov Report

Merging #129 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff          @@
##           master   #129   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files          15     15           
  Lines         737    737           
  Branches       28     28           
=====================================
  Hits          737    737

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 7b794c4...a90d3bc. Read the comment docs.