build(deps): bump github.com/docker/buildx from 0.21.1 to 0.21.2

Bumps [github.com/docker/buildx](https://github.com/docker/buildx) from 0.21.1 to 0.21.2.
- [Release notes](https://github.com/docker/buildx/releases)
- [Commits](docker/buildx@v0.21.1...v0.21.2)

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

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

go.mod

@@ -12,7 +12,7 @@ require (
 	github.com/containerd/platforms v1.0.0-rc.1
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc
 	github.com/distribution/reference v0.6.0
-	github.com/docker/buildx v0.21.1
+	github.com/docker/buildx v0.21.2
 	github.com/docker/cli v28.0.1+incompatible
 	github.com/docker/cli-docs-tool v0.9.0
 	github.com/docker/docker v28.0.1+incompatible

go.sum

@@ -127,8 +127,8 @@ github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc/go.mod h1:J7Y8Yc
 github.com/denisenkom/go-mssqldb v0.0.0-20191128021309-1d7a30a10f73/go.mod h1:xbL0rPBG9cCiLr28tMa8zpbdarY27NDyej4t/EjAShU=
 github.com/distribution/reference v0.6.0 h1:0IXCQ5g4/QMHHkarYzh5l+u8T3t73zM5QvfrDyIgxBk=
 github.com/distribution/reference v0.6.0/go.mod h1:BbU0aIcezP1/5jX/8MP0YiH4SdvB5Y4f/wlDRiLyi3E=
-github.com/docker/buildx v0.21.1 h1:YjV2k6CsSDbkDTOMsjARUIrj2xv+zZR+M2dtrRyzXhg=
-github.com/docker/buildx v0.21.1/go.mod h1:8V4UMnlKsaGYwz83BygmIbJIFEAYGHT6KAv8akDZmqo=
+github.com/docker/buildx v0.21.2 h1:r09paH8q9nvAX2PR1ntRrc+C6FBH93bvKUsn1WOb/jU=
+github.com/docker/buildx v0.21.2/go.mod h1:8V4UMnlKsaGYwz83BygmIbJIFEAYGHT6KAv8akDZmqo=
 github.com/docker/cli v28.0.1+incompatible h1:g0h5NQNda3/CxIsaZfH4Tyf6vpxFth7PYl3hgCPOKzs=
 github.com/docker/cli v28.0.1+incompatible/go.mod h1:JLrzqnKDaYBop7H2jaqPtU4hHvMKP+vjCwu2uszcLI8=
 github.com/docker/cli-docs-tool v0.9.0 h1:CVwQbE+ZziwlPqrJ7LRyUF6GvCA+6gj7MTCsayaK9t0=