chore(deps): bump github.com/coreos/butane from 0.20.0 to 0.21.0

Bumps [github.com/coreos/butane](https://github.com/coreos/butane) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/coreos/butane/releases)
- [Changelog](https://github.com/coreos/butane/blob/main/docs/release-notes.md)
- [Commits](coreos/butane@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: github.com/coreos/butane
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/Masterminds/sprig v2.22.0+incompatible
 	github.com/ahmetb/gen-crd-api-reference-docs v0.3.0
 	github.com/aws/aws-sdk-go v1.54.11
-	github.com/coreos/butane v0.20.0
+	github.com/coreos/butane v0.21.0
 	github.com/coreos/go-systemd/v22 v22.5.0
 	github.com/gardener/etcd-druid v0.22.0
 	github.com/gardener/gardener v1.90.4
@@ -49,7 +49,7 @@ require (
 	github.com/clarketm/json v1.17.1 // indirect
 	github.com/coreos/go-json v0.0.0-20230131223807-18775e0fb4fb // indirect
 	github.com/coreos/go-semver v0.3.1 // indirect
-	github.com/coreos/ignition/v2 v2.17.0 // indirect
+	github.com/coreos/ignition/v2 v2.18.0 // indirect
 	github.com/coreos/vcontext v0.0.0-20230201181013-d72178a18687 // indirect
 	github.com/cyphar/filepath-securejoin v0.2.4 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect

go.sum

@@ -61,16 +61,16 @@ github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMn
 github.com/clarketm/json v1.17.1 h1:U1IxjqJkJ7bRK4L6dyphmoO840P6bdhPdbbLySourqI=
 github.com/clarketm/json v1.17.1/go.mod h1:ynr2LRfb0fQU34l07csRNBTcivjySLLiY1YzQqKVfdo=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
-github.com/coreos/butane v0.20.0 h1:lKdyBDazlM5cenywmAT6Fcwp5B2rVeYtIqZDSbYu3MA=
-github.com/coreos/butane v0.20.0/go.mod h1:JPxQB/3omxqSg1ZWAOg5x3aslzx4nDvmb7Wyv8gC150=
+github.com/coreos/butane v0.21.0 h1:GDi6XBheEfvxaq7Ez3wxdN+0IraAz3U7QvpVGcbHd84=
+github.com/coreos/butane v0.21.0/go.mod h1:3OKS5qaH58O2yLAKgAtOgBpUQSm7aIOU09IpG+IvmF4=
 github.com/coreos/go-json v0.0.0-20230131223807-18775e0fb4fb h1:rmqyI19j3Z/74bIRhuC59RB442rXUazKNueVpfJPxg4=
 github.com/coreos/go-json v0.0.0-20230131223807-18775e0fb4fb/go.mod h1:rcFZM3uxVvdyNmsAV2jopgPD1cs5SPWJWU5dOz2LUnw=
 github.com/coreos/go-semver v0.3.1 h1:yi21YpKnrx1gt5R+la8n5WgS0kCrsPp33dmEyHReZr4=
 github.com/coreos/go-semver v0.3.1/go.mod h1:irMmmIw/7yzSRPWryHsK7EYSg09caPQL03VsM8rvUec=
 github.com/coreos/go-systemd/v22 v22.5.0 h1:RrqgGjYQKalulkV8NGVIfkXQf6YYmOyiJKk8iXXhfZs=
 github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
-github.com/coreos/ignition/v2 v2.17.0 h1:bBqoZ9HYuIq20hbkb1ucypA7tMi9k/iouPnLNFZQXGM=
-github.com/coreos/ignition/v2 v2.17.0/go.mod h1:BFL205qhVgftPJ1nej+C/VPrK6Hl3LlZUhqmhV/HUuA=
+github.com/coreos/ignition/v2 v2.18.0 h1:sPSGGsxaCuFMpKOMBQ71I9RIR20SIF4dWnoTomcPEYQ=
+github.com/coreos/ignition/v2 v2.18.0/go.mod h1:TURPHDqWUWTmej8c+CEMBENMU3N/Lt6GfreHJuoDMbA=
 github.com/coreos/vcontext v0.0.0-20230201181013-d72178a18687 h1:uSmlDgJGbUB0bwQBcZomBTottKwEDF5fF8UjSwKSzWM=
 github.com/coreos/vcontext v0.0.0-20230201181013-d72178a18687/go.mod h1:Salmysdw7DAVuobBW/LwsKKgpyCPHUhjyJoMJD+ZJiI=
 github.com/cpuguy83/go-md2man/v2 v2.0.4/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=