chore(deps): bump github.com/hashicorp/terraform-plugin-mux (#3350)

Bumps [github.com/hashicorp/terraform-plugin-mux](https://github.com/hashicorp/terraform-plugin-mux) from 0.20.0 to 0.21.0.
- [Release notes](https://github.com/hashicorp/terraform-plugin-mux/releases)
- [Changelog](https://github.com/hashicorp/terraform-plugin-mux/blob/main/CHANGELOG.md)
- [Commits](hashicorp/terraform-plugin-mux@v0.20.0...v0.21.0)

---
updated-dependencies:
- dependency-name: github.com/hashicorp/terraform-plugin-mux
  dependency-version: 0.21.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

go.mod

@@ -23,7 +23,7 @@ require (
 	github.com/hashicorp/go-retryablehttp v0.7.8
 	github.com/hashicorp/terraform-plugin-go v0.29.0
 	github.com/hashicorp/terraform-plugin-log v0.9.0
-	github.com/hashicorp/terraform-plugin-mux v0.20.0
+	github.com/hashicorp/terraform-plugin-mux v0.21.0
 	github.com/hashicorp/terraform-plugin-sdk/v2 v2.38.0
 	github.com/hashicorp/terraform-plugin-testing v1.13.3
 	github.com/nats-io/jwt/v2 v2.8.0

go.sum

@@ -329,8 +329,8 @@ github.com/hashicorp/terraform-plugin-go v0.29.0 h1:1nXKl/nSpaYIUBU1IG/EsDOX0vv+
 github.com/hashicorp/terraform-plugin-go v0.29.0/go.mod h1:vYZbIyvxyy0FWSmDHChCqKvI40cFTDGSb3D8D70i9GM=
 github.com/hashicorp/terraform-plugin-log v0.9.0 h1:i7hOA+vdAItN1/7UrfBqBwvYPQ9TFvymaRGZED3FCV0=
 github.com/hashicorp/terraform-plugin-log v0.9.0/go.mod h1:rKL8egZQ/eXSyDqzLUuwUYLVdlYeamldAHSxjUFADow=
-github.com/hashicorp/terraform-plugin-mux v0.20.0 h1:3QpBnI9uCuL0Yy2Rq/kR9cOdmOFNhw88A2GoZtk5aXM=
-github.com/hashicorp/terraform-plugin-mux v0.20.0/go.mod h1:wSIZwJjSYk86NOTX3fKUlThMT4EAV1XpBHz9SAvjQr4=
+github.com/hashicorp/terraform-plugin-mux v0.21.0 h1:QsEYnzSD2c3zT8zUrUGqaFGhV/Z8zRUlU7FY3ZPJFfw=
+github.com/hashicorp/terraform-plugin-mux v0.21.0/go.mod h1:Qpt8+6AD7NmL0DS7ASkN0EXpDQ2J/FnnIgeUr1tzr5A=
 github.com/hashicorp/terraform-plugin-sdk/v2 v2.38.0 h1:PQP7Crrc7t/ozj+P9x0/lsTzGNy3lVppH8zAJylofaE=
 github.com/hashicorp/terraform-plugin-sdk/v2 v2.38.0/go.mod h1:GQhpKVvvuwzD79e8/NZ+xzj+ZpWovdPAe8nfV/skwNU=
 github.com/hashicorp/terraform-plugin-testing v1.13.3 h1:QLi/khB8Z0a5L54AfPrHukFpnwsGL8cwwswj4RZduCo=