chore(deps): update dependency markdownlint-cli2 to v0.21.0 (#1022)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

mise.toml

@@ -3,7 +3,7 @@ lychee = "0.23.0"
 k3d = "5.8.2"
 "go:github.com/grafana/oats" = "0.6.1"
 kubectl = "1.35.1"
-markdownlint-cli2 = "0.20.0"
+markdownlint-cli2 = "0.21.0"
 
 [settings]
 # Only install tools explicitly defined in the [tools] section above