build(deps): bump github.com/docker/buildx from 0.28.0-rc2 to 0.28.0

Bumps [github.com/docker/buildx](https://github.com/docker/buildx) from 0.28.0-rc2 to 0.28.0.
- [Release notes](https://github.com/docker/buildx/releases)
- [Commits](https://github.com/docker/buildx/compare/v0.28.0-rc2...v0.28.0)

---
updated-dependencies:
- dependency-name: github.com/docker/buildx
  dependency-version: 0.28.0
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/containerd/platforms v1.0.0-rc.1
 	github.com/davecgh/go-spew v1.1.1
 	github.com/distribution/reference v0.6.0
-	github.com/docker/buildx v0.28.0-rc2
+	github.com/docker/buildx v0.28.0
 	github.com/docker/cli v28.4.0+incompatible
 	github.com/docker/cli-docs-tool v0.10.0
 	github.com/docker/docker v28.4.0+incompatible

go.sum

@@ -126,8 +126,8 @@ github.com/distribution/reference v0.6.0 h1:0IXCQ5g4/QMHHkarYzh5l+u8T3t73zM5Qvfr
 github.com/distribution/reference v0.6.0/go.mod h1:BbU0aIcezP1/5jX/8MP0YiH4SdvB5Y4f/wlDRiLyi3E=
 github.com/dlclark/regexp2 v1.11.0 h1:G/nrcoOa7ZXlpoa/91N3X7mM3r8eIlMBBJZvsz/mxKI=
 github.com/dlclark/regexp2 v1.11.0/go.mod h1:DHkYz0B9wPfa6wondMfaivmHpzrQ3v9q8cnmRbL6yW8=
-github.com/docker/buildx v0.28.0-rc2 h1:UYwiYhk9B0Wkw0cTWjoP7caujfwvsSJfxu41xheXQQ8=
-github.com/docker/buildx v0.28.0-rc2/go.mod h1:nhsrcN6qzbyOZWsXHwc/nqr70CdvJ7b6CEOEMQ1/0KY=
+github.com/docker/buildx v0.28.0 h1:ZnrVsZ/qQwSOQ4Fx3IgXjiurAwvocaF1YUaPbIXD89E=
+github.com/docker/buildx v0.28.0/go.mod h1:nLwx58w7xrQbLVSXiWiHpkVhY4ou4ci/hYomc139Vjk=
 github.com/docker/cli v28.4.0+incompatible h1:RBcf3Kjw2pMtwui5V0DIMdyeab8glEw5QY0UUU4C9kY=
 github.com/docker/cli v28.4.0+incompatible/go.mod h1:JLrzqnKDaYBop7H2jaqPtU4hHvMKP+vjCwu2uszcLI8=
 github.com/docker/cli-docs-tool v0.10.0 h1:bOD6mKynPQgojQi3s2jgcUWGp/Ebqy1SeCr9VfKQLLU=