Bump github.com/gaissmai/bart from 0.20.1 to 0.20.4 (#1391)

* Bump github.com/gaissmai/bart from 0.20.1 to 0.20.4

Bumps [github.com/gaissmai/bart](https://github.com/gaissmai/bart) from 0.20.1 to 0.20.4.
- [Release notes](https://github.com/gaissmai/bart/releases)
- [Commits](https://github.com/gaissmai/bart/compare/v0.20.1...v0.20.4)

---
updated-dependencies:
- dependency-name: github.com/gaissmai/bart
  dependency-version: 0.20.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

* set back to go 1.23.0

We were only on 1.23.6 because of bart in the first place.

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Wade Simmons <wsimmons@slack-corp.com>

go.mod

@@ -1,6 +1,6 @@
 module github.com/slackhq/nebula
 
-go 1.23.6
+go 1.23.0
 
 toolchain go1.24.1
 
@@ -10,7 +10,7 @@ require (
 	github.com/armon/go-radix v1.0.0
 	github.com/cyberdelia/go-metrics-graphite v0.0.0-20161219230853-39f87cc3b432
 	github.com/flynn/noise v1.1.0
-	github.com/gaissmai/bart v0.20.1
+	github.com/gaissmai/bart v0.20.4
 	github.com/gogo/protobuf v1.3.2
 	github.com/google/gopacket v1.1.19
 	github.com/kardianos/service v1.2.2