Update module github.com/rancher/fleet/pkg/apis to v0.15.4 (#5437)

Co-authored-by: renovate-rancher[bot] <119870437+renovate-rancher[bot]@users.noreply.github.com>

Author: renovate-rancher[bot]

pkg/helmvalues/go.mod

@@ -6,7 +6,7 @@ toolchain go1.26.5
 
 replace github.com/rancher/fleet/pkg/apis => ../apis
 
-require github.com/rancher/fleet/pkg/apis v0.15.2
+require github.com/rancher/fleet/pkg/apis v0.15.4
 
 require (
 	github.com/fxamacker/cbor/v2 v2.9.0 // indirect